diff --git a/.clang-format b/.clang-format
index a22e5e692..192188e84 100644
--- a/.clang-format
+++ b/.clang-format
@@ -59,12 +59,12 @@ ForEachMacros:
   - foreach
   - Q_FOREACH
   - BOOST_FOREACH
-IncludeBlocks:   Preserve
+IncludeBlocks:   Regroup
 IncludeCategories:
-  - Regex:           '^(<|"(gtest|gmock|isl|json)/)'
-    Priority:        4
-  - Regex:           '.*'
-    Priority:        3
+  - Regex:           '<[[:alnum:]._]+>'
+    Priority:        5
+  - Regex:           '^(<"podio/)'
+    Priority:        1
 IncludeIsMainRegex: '(Test)?$'
 IndentCaseLabels: false
 IndentPPDirectives: BeforeHash
diff --git a/include/podio/CollectionBufferFactory.h b/include/podio/CollectionBufferFactory.h
index 531e54150..2828fa77d 100644
--- a/include/podio/CollectionBufferFactory.h
+++ b/include/podio/CollectionBufferFactory.h
@@ -6,6 +6,7 @@
 
 #include <functional>
 #include <optional>
+#include <string>
 #include <unordered_map>
 #include <vector>
 
diff --git a/include/podio/DatamodelRegistry.h b/include/podio/DatamodelRegistry.h
index cbfa294cd..a3d255543 100644
--- a/include/podio/DatamodelRegistry.h
+++ b/include/podio/DatamodelRegistry.h
@@ -1,6 +1,7 @@
 #ifndef PODIO_DATAMODELREGISTRY_H
 #define PODIO_DATAMODELREGISTRY_H
 
+#include <cstddef>
 #include <string>
 #include <string_view>
 #include <tuple>
diff --git a/include/podio/GenericParameters.h b/include/podio/GenericParameters.h
index 4f41aad63..d935864d5 100644
--- a/include/podio/GenericParameters.h
+++ b/include/podio/GenericParameters.h
@@ -5,6 +5,8 @@
 #include "podio/utilities/TypeHelpers.h"
 
 #include <algorithm>
+#include <cstddef>
+#include <initializer_list>
 #include <iostream>
 #include <iterator>
 #include <map>
@@ -12,6 +14,9 @@
 #include <mutex>
 #include <optional>
 #include <string>
+#include <tuple>
+#include <type_traits>
+#include <utility>
 #include <vector>
 
 #if PODIO_ENABLE_SIO
diff --git a/include/podio/RNTupleReader.h b/include/podio/RNTupleReader.h
index 373e7c45f..3c1279f12 100644
--- a/include/podio/RNTupleReader.h
+++ b/include/podio/RNTupleReader.h
@@ -1,23 +1,24 @@
 #ifndef PODIO_RNTUPLEREADER_H
 #define PODIO_RNTUPLEREADER_H
 
+#include "podio/GenericParameters.h"
 #include "podio/ROOTFrameData.h"
 #include "podio/SchemaEvolution.h"
 #include "podio/podioVersion.h"
 #include "podio/utilities/DatamodelRegistryIOHelpers.h"
+#include <ROOT/RVersion.hxx>
+#if ROOT_VERSION_CODE >= ROOT_VERSION(6, 31, 0)
+  #include <ROOT/RNTupleReader.hxx>
+#endif
 
+#include <memory>
 #include <string>
 #include <string_view>
 #include <unordered_map>
 #include <vector>
 
-#include <ROOT/RNTuple.hxx>
-#include <RVersion.h>
-#if ROOT_VERSION_CODE >= ROOT_VERSION(6, 31, 0)
-  #include <ROOT/RNTupleReader.hxx>
-#endif
-
 namespace podio {
+class CollectionIDTable;
 
 /**
 This class has the function to read available data from disk
diff --git a/include/podio/RNTupleWriter.h b/include/podio/RNTupleWriter.h
index b57eb09b3..011918afa 100644
--- a/include/podio/RNTupleWriter.h
+++ b/include/podio/RNTupleWriter.h
@@ -1,23 +1,33 @@
 #ifndef PODIO_RNTUPLEWRITER_H
 #define PODIO_RNTUPLEWRITER_H
 
-#include "podio/Frame.h"
+#include "TFile.h"
 #include "podio/SchemaEvolution.h"
 #include "podio/utilities/DatamodelRegistryIOHelpers.h"
 #include "podio/utilities/RootHelpers.h"
-
-#include "TFile.h"
-#include <ROOT/RNTuple.hxx>
 #include <ROOT/RNTupleModel.hxx>
+#include <ROOT/RVersion.hxx>
+
+#include <cstdint>
+
+namespace ROOT {
+namespace Experimental {
+  class REntry;
+} // namespace Experimental
+} // namespace ROOT
 #if ROOT_VERSION_CODE >= ROOT_VERSION(6, 31, 0)
   #include <ROOT/RNTupleWriter.hxx>
 #endif
 
+#include <memory>
 #include <string>
+#include <tuple>
 #include <unordered_map>
 #include <vector>
 
 namespace podio {
+class Frame;
+class GenericParameters;
 
 /// The RNTupleWriter writes podio files into ROOT files using the new RNTuple
 /// format.
diff --git a/include/podio/ROOTFrameData.h b/include/podio/ROOTFrameData.h
index 502ff24ef..0b439b884 100644
--- a/include/podio/ROOTFrameData.h
+++ b/include/podio/ROOTFrameData.h
@@ -9,6 +9,7 @@
 #include <optional>
 #include <string>
 #include <unordered_map>
+#include <vector>
 
 namespace podio {
 
diff --git a/include/podio/ROOTLegacyReader.h b/include/podio/ROOTLegacyReader.h
index 9383ca51b..0794b10e5 100644
--- a/include/podio/ROOTLegacyReader.h
+++ b/include/podio/ROOTLegacyReader.h
@@ -1,12 +1,11 @@
 #ifndef PODIO_ROOTLEGACYREADER_H
 #define PODIO_ROOTLEGACYREADER_H
 
+#include "TChain.h"
 #include "podio/ROOTFrameData.h"
 #include "podio/podioVersion.h"
 #include "podio/utilities/RootHelpers.h"
 
-#include "TChain.h"
-
 #include <memory>
 #include <string>
 #include <tuple>
diff --git a/include/podio/ROOTReader.h b/include/podio/ROOTReader.h
index e6ecbd0e0..1af6884c2 100644
--- a/include/podio/ROOTReader.h
+++ b/include/podio/ROOTReader.h
@@ -1,25 +1,22 @@
 #ifndef PODIO_ROOTREADER_H
 #define PODIO_ROOTREADER_H
 
+#include "TChain.h"
 #include "podio/ROOTFrameData.h"
+#include "podio/SchemaEvolution.h"
 #include "podio/podioVersion.h"
 #include "podio/utilities/DatamodelRegistryIOHelpers.h"
 #include "podio/utilities/RootHelpers.h"
 
-#include "TChain.h"
-
+#include <cstddef>
 #include <memory>
 #include <string>
 #include <string_view>
 #include <tuple>
+#include <unordered_map>
 #include <utility>
 #include <vector>
 
-// forward declarations
-class TClass;
-class TFile;
-class TTree;
-
 namespace podio {
 
 namespace detail {
@@ -30,7 +27,6 @@ namespace detail {
 
 } // namespace detail
 
-class CollectionBase;
 class CollectionIDTable;
 class GenericParameters;
 struct CollectionReadBuffers;
diff --git a/include/podio/ROOTWriter.h b/include/podio/ROOTWriter.h
index 5ee23835f..e2f3d4b23 100644
--- a/include/podio/ROOTWriter.h
+++ b/include/podio/ROOTWriter.h
@@ -1,12 +1,11 @@
 #ifndef PODIO_ROOTWRITER_H
 #define PODIO_ROOTWRITER_H
 
+#include "TFile.h"
 #include "podio/CollectionIDTable.h"
 #include "podio/utilities/DatamodelRegistryIOHelpers.h"
 #include "podio/utilities/RootHelpers.h"
 
-#include "TFile.h"
-
 #include <memory>
 #include <string>
 #include <tuple>
@@ -18,7 +17,6 @@ class TTree;
 
 namespace podio {
 class Frame;
-class CollectionBase;
 class GenericParameters;
 
 /// The ROOTWriter writes podio files into ROOT files using TTrees.
diff --git a/include/podio/Reader.h b/include/podio/Reader.h
index ee8eaa682..6071c3a89 100644
--- a/include/podio/Reader.h
+++ b/include/podio/Reader.h
@@ -2,8 +2,16 @@
 #define PODIO_READER_H
 
 #include "podio/Frame.h"
+#include "podio/FrameCategories.h"
 #include "podio/podioVersion.h"
 
+#include <cstddef>
+#include <memory>
+#include <stdexcept>
+#include <string>
+#include <string_view>
+#include <vector>
+
 namespace podio {
 
 /// Generic (type erased) reader class that can handle different I/O backends
diff --git a/include/podio/SIOBlock.h b/include/podio/SIOBlock.h
index 3ae41651e..839748de6 100644
--- a/include/podio/SIOBlock.h
+++ b/include/podio/SIOBlock.h
@@ -6,7 +6,6 @@
 #include <podio/GenericParameters.h>
 #include <podio/podioVersion.h>
 #include <podio/utilities/TypeHelpers.h>
-
 #include <sio/block.h>
 #include <sio/io_device.h>
 #include <sio/version.h>
diff --git a/include/podio/SIOBlockUserData.h b/include/podio/SIOBlockUserData.h
index 4d3110fba..f6618213e 100644
--- a/include/podio/SIOBlockUserData.h
+++ b/include/podio/SIOBlockUserData.h
@@ -5,7 +5,6 @@
 #include "podio/CollectionBuffers.h"
 #include "podio/SIOBlock.h"
 #include "podio/UserDataCollection.h"
-
 #include <sio/api.h>
 #include <sio/io_device.h>
 #include <sio/version.h>
diff --git a/include/podio/SIOFrameData.h b/include/podio/SIOFrameData.h
index 95b09d927..5e778b32d 100644
--- a/include/podio/SIOFrameData.h
+++ b/include/podio/SIOFrameData.h
@@ -5,7 +5,6 @@
 #include "podio/CollectionIDTable.h"
 #include "podio/GenericParameters.h"
 #include "podio/SIOBlock.h"
-
 #include <sio/buffer.h>
 #include <sio/definitions.h>
 
diff --git a/include/podio/SIOLegacyReader.h b/include/podio/SIOLegacyReader.h
index d490fcd5e..a77ffbb08 100644
--- a/include/podio/SIOLegacyReader.h
+++ b/include/podio/SIOLegacyReader.h
@@ -4,7 +4,6 @@
 #include "podio/SIOBlock.h"
 #include "podio/SIOFrameData.h"
 #include "podio/podioVersion.h"
-
 #include <sio/definitions.h>
 
 #include <memory>
diff --git a/include/podio/SIOReader.h b/include/podio/SIOReader.h
index 80970abbb..e01163f74 100644
--- a/include/podio/SIOReader.h
+++ b/include/podio/SIOReader.h
@@ -5,7 +5,6 @@
 #include "podio/SIOFrameData.h"
 #include "podio/podioVersion.h"
 #include "podio/utilities/DatamodelRegistryIOHelpers.h"
-
 #include <sio/definitions.h>
 
 #include <memory>
diff --git a/include/podio/SIOWriter.h b/include/podio/SIOWriter.h
index 6f680ffb8..381452c50 100644
--- a/include/podio/SIOWriter.h
+++ b/include/podio/SIOWriter.h
@@ -3,7 +3,6 @@
 
 #include "podio/SIOBlock.h"
 #include "podio/utilities/DatamodelRegistryIOHelpers.h"
-
 #include <sio/definitions.h>
 
 #include <string>
diff --git a/include/podio/SchemaEvolution.h b/include/podio/SchemaEvolution.h
index cb8803d26..e82b96fb1 100644
--- a/include/podio/SchemaEvolution.h
+++ b/include/podio/SchemaEvolution.h
@@ -1,6 +1,7 @@
 #ifndef PODIO_SCHEMAEVOLUTION_H
 #define PODIO_SCHEMAEVOLUTION_H
 
+#include <cstddef>
 #include <cstdint>
 #include <functional>
 #include <string>
diff --git a/include/podio/UserDataCollection.h b/include/podio/UserDataCollection.h
index 63660a72f..9e13ea8bd 100644
--- a/include/podio/UserDataCollection.h
+++ b/include/podio/UserDataCollection.h
@@ -7,6 +7,18 @@
 #include "podio/SchemaEvolution.h"
 #include "podio/utilities/TypeHelpers.h"
 
+#include <cstddef>
+#include <cstdint>
+#include <iostream>
+#include <string_view>
+#include <tuple>
+#include <type_traits>
+#include <vector>
+
+namespace podio {
+class ICollectionProvider;
+} // namespace podio
+
 #define PODIO_ADD_USER_TYPE(type)                                                                                      \
   template <>                                                                                                          \
   constexpr const char* userDataTypeName<type>() {                                                                     \
diff --git a/include/podio/Writer.h b/include/podio/Writer.h
index 9f2c4d85e..23ff6e56f 100644
--- a/include/podio/Writer.h
+++ b/include/podio/Writer.h
@@ -2,6 +2,11 @@
 #define PODIO_WRITER_H
 
 #include "podio/Frame.h"
+#include "podio/FrameCategories.h"
+
+#include <memory>
+#include <string>
+#include <vector>
 
 namespace podio {
 
diff --git a/include/podio/utilities/DatamodelRegistryIOHelpers.h b/include/podio/utilities/DatamodelRegistryIOHelpers.h
index 77416a839..ae82bc716 100644
--- a/include/podio/utilities/DatamodelRegistryIOHelpers.h
+++ b/include/podio/utilities/DatamodelRegistryIOHelpers.h
@@ -1,15 +1,16 @@
 #ifndef PODIO_UTILITIES_DATAMODELREGISTRYIOHELPERS_H
 #define PODIO_UTILITIES_DATAMODELREGISTRYIOHELPERS_H
 
-#include "podio/CollectionBase.h"
-#include "podio/DatamodelRegistry.h"
-
+#include <cstddef>
 #include <set>
 #include <string>
+#include <string_view>
 #include <tuple>
+#include <utility>
 #include <vector>
 
 namespace podio {
+class CollectionBase;
 
 /// Helper class to collect the datamodel (JSON) definitions that should be
 /// written.
diff --git a/include/podio/utilities/RootHelpers.h b/include/podio/utilities/RootHelpers.h
index 360ef6674..684455bc3 100644
--- a/include/podio/utilities/RootHelpers.h
+++ b/include/podio/utilities/RootHelpers.h
@@ -3,13 +3,19 @@
 
 #include "podio/GenericParameters.h"
 
-#include "ROOT/RVec.hxx"
-#include "TBranch.h"
-
+#include <cstdint>
 #include <string>
 #include <tuple>
 #include <vector>
 
+class TBranch;
+namespace ROOT {
+namespace VecOps {
+  template <typename T>
+  class RVec;
+} // namespace VecOps
+} // namespace ROOT
+
 namespace podio {
 class CollectionBase;
 
diff --git a/src/CollectionBufferFactory.cc b/src/CollectionBufferFactory.cc
index 8c48ea083..e72419b9d 100644
--- a/src/CollectionBufferFactory.cc
+++ b/src/CollectionBufferFactory.cc
@@ -1,6 +1,10 @@
 #include "podio/CollectionBufferFactory.h"
+
 #include "podio/CollectionBuffers.h"
 
+#include <cstddef>
+#include <utility>
+
 namespace podio {
 CollectionBufferFactory& CollectionBufferFactory::mutInstance() {
   static CollectionBufferFactory factory;
diff --git a/src/CollectionIDTable.cc b/src/CollectionIDTable.cc
index ace8a91fe..86670b4f7 100644
--- a/src/CollectionIDTable.cc
+++ b/src/CollectionIDTable.cc
@@ -4,7 +4,10 @@
 #include "MurmurHash3.h"
 
 #include <algorithm>
+#include <cstddef>
 #include <iostream>
+#include <iterator>
+#include <utility>
 
 namespace podio {
 
diff --git a/src/DataSource.cc b/src/DataSource.cc
index cdc678a98..ce52c1669 100644
--- a/src/DataSource.cc
+++ b/src/DataSource.cc
@@ -1,4 +1,5 @@
 #include "podio/DataSource.h"
+
 #include "podio/Reader.h"
 
 // podio
diff --git a/src/DatamodelRegistryIOHelpers.cc b/src/DatamodelRegistryIOHelpers.cc
index 1e7573a1f..0e438d436 100644
--- a/src/DatamodelRegistryIOHelpers.cc
+++ b/src/DatamodelRegistryIOHelpers.cc
@@ -1,5 +1,10 @@
 #include "podio/utilities/DatamodelRegistryIOHelpers.h"
+
+#include "podio/CollectionBase.h"
+#include "podio/DatamodelRegistry.h"
+
 #include <algorithm>
+#include <iostream>
 #include <iterator>
 
 namespace podio {
diff --git a/src/RNTupleReader.cc b/src/RNTupleReader.cc
index d391e578a..cd2153c09 100644
--- a/src/RNTupleReader.cc
+++ b/src/RNTupleReader.cc
@@ -1,14 +1,26 @@
 #include "podio/RNTupleReader.h"
+
 #include "podio/CollectionBufferFactory.h"
 #include "podio/CollectionBuffers.h"
 #include "podio/CollectionIDTable.h"
 #include "podio/DatamodelRegistry.h"
 #include "podio/GenericParameters.h"
+#include "podio/ObjectID.h"
 #include "rootUtils.h"
-
+#include <ROOT/REntry.hxx>
 #include <ROOT/RError.hxx>
+#include <ROOT/RNTupleModel.hxx>
+#include <ROOT/RNTupleView.hxx>
 
+#include <algorithm>
+#include <cstddef>
+#include <cstdint>
+#include <iostream>
 #include <memory>
+#include <numeric>
+#include <optional>
+#include <tuple>
+#include <utility>
 
 namespace podio {
 
diff --git a/src/RNTupleWriter.cc b/src/RNTupleWriter.cc
index caa18a5cb..f9a6d2cdb 100644
--- a/src/RNTupleWriter.cc
+++ b/src/RNTupleWriter.cc
@@ -1,15 +1,23 @@
 #include "podio/RNTupleWriter.h"
+
+#include "TFile.h"
+#include "podio/CollectionBuffers.h"
 #include "podio/DatamodelRegistry.h"
+#include "podio/Frame.h"
 #include "podio/SchemaEvolution.h"
 #include "podio/podioVersion.h"
 #include "rootUtils.h"
-
-#include "TFile.h"
-
+#include <ROOT/REntry.hxx>
+#include <ROOT/RError.hxx>
 #include <ROOT/RField.hxx>
 #include <ROOT/RNTupleModel.hxx>
 
+#include <stdexcept>
+#include <utility>
+
 namespace podio {
+class CollectionBase;
+class GenericParameters;
 
 RNTupleWriter::RNTupleWriter(const std::string& filename) :
     m_file(new TFile(filename.c_str(), "RECREATE", "data file")) {
diff --git a/src/ROOTFrameData.cc b/src/ROOTFrameData.cc
index 2fde64154..45ec57ebc 100644
--- a/src/ROOTFrameData.cc
+++ b/src/ROOTFrameData.cc
@@ -1,5 +1,8 @@
 #include "podio/ROOTFrameData.h"
 
+#include <functional>
+#include <utility>
+
 namespace podio {
 
 ROOTFrameData::ROOTFrameData(BufferMap&& buffers, CollIDPtr&& idTable, podio::GenericParameters&& params) :
diff --git a/src/ROOTLegacyReader.cc b/src/ROOTLegacyReader.cc
index 4a431dc42..df9232867 100644
--- a/src/ROOTLegacyReader.cc
+++ b/src/ROOTLegacyReader.cc
@@ -8,6 +8,8 @@
 #include "podio/CollectionIDTable.h"
 #include "podio/GenericParameters.h"
 #include "podio/ROOTLegacyReader.h"
+#include "podio/podioVersion.h"
+#include "podio/utilities/RootHelpers.h"
 
 // ROOT specific includes
 #include "TChain.h"
@@ -15,6 +17,18 @@
 #include "TFile.h"
 #include "TTree.h"
 
+#include <cstddef>
+#include <functional>
+#include <iostream>
+#include <memory>
+#include <optional>
+#include <stdexcept>
+#include <string>
+#include <string_view>
+#include <tuple>
+#include <utility>
+#include <vector>
+
 namespace podio {
 
 std::unique_ptr<ROOTFrameData> ROOTLegacyReader::readNextEntry(const std::string& name) {
diff --git a/src/ROOTReader.cc b/src/ROOTReader.cc
index 1b4971601..f84b209a5 100644
--- a/src/ROOTReader.cc
+++ b/src/ROOTReader.cc
@@ -1,4 +1,5 @@
 #include "podio/ROOTReader.h"
+
 #include "podio/CollectionBase.h"
 #include "podio/CollectionBufferFactory.h"
 #include "podio/CollectionBuffers.h"
@@ -8,13 +9,19 @@
 #include "podio/utilities/RootHelpers.h"
 #include "rootUtils.h"
 
+#include <TBranch.h>
+#include <TObjArray.h>
+#include <TObject.h>
+#include <algorithm>
+#include <compare>
+#include <functional>
+#include <optional>
+#include <stdexcept>
+#include <unordered_map>
 // ROOT specific includes
 #include "TChain.h"
 #include "TClass.h"
 
-#include <stdexcept>
-#include <unordered_map>
-
 namespace podio {
 
 std::tuple<std::vector<root_utils::CollectionBranches>, std::vector<std::pair<std::string, detail::CollectionInfo>>>
diff --git a/src/ROOTWriter.cc b/src/ROOTWriter.cc
index 33f02741e..f858cdf83 100644
--- a/src/ROOTWriter.cc
+++ b/src/ROOTWriter.cc
@@ -1,13 +1,20 @@
 #include "podio/ROOTWriter.h"
+
+#include "TTree.h"
+#include "podio/CollectionBuffers.h"
 #include "podio/DatamodelRegistry.h"
 #include "podio/Frame.h"
 #include "podio/GenericParameters.h"
 #include "podio/podioVersion.h"
-
 #include "rootUtils.h"
 
-#include "TTree.h"
+#include <TBranch.h>
+#include <TFile.h>
+#include <cstddef>
+#include <optional>
+#include <stdexcept>
 #include <tuple>
+#include <utility>
 
 namespace podio {
 
diff --git a/src/Reader.cc b/src/Reader.cc
index f43fc432a..d4f93144a 100644
--- a/src/Reader.cc
+++ b/src/Reader.cc
@@ -1,6 +1,10 @@
 #include "podio/Reader.h"
 
 #include "podio/ROOTReader.h"
+
+#include <TCollection.h>
+#include <TList.h>
+#include <TObject.h>
 #if PODIO_ENABLE_RNTUPLE
   #include "podio/RNTupleReader.h"
 #endif
@@ -10,7 +14,9 @@
 
 #include "TFile.h"
 #include "TKey.h"
+
 #include <memory>
+#include <utility>
 
 namespace podio {
 
diff --git a/src/RootHelpers.cc b/src/RootHelpers.cc
index a1a33484c..c933ec392 100644
--- a/src/RootHelpers.cc
+++ b/src/RootHelpers.cc
@@ -1,5 +1,9 @@
 #include "podio/utilities/RootHelpers.h"
 
+#include <ROOT/RVec.hxx>
+
+#include <utility>
+
 namespace podio::root_utils {
 GenericParameters
 loadParamsFrom(ROOT::VecOps::RVec<std::string> intKeys, ROOT::VecOps::RVec<std::vector<int>> intValues,
diff --git a/src/SIOBlock.cc b/src/SIOBlock.cc
index 61fb96182..60be3bcc7 100644
--- a/src/SIOBlock.cc
+++ b/src/SIOBlock.cc
@@ -1,10 +1,11 @@
 #include "podio/SIOBlock.h"
 
+#include "podio/GenericParameters.h"
+
 #include <algorithm>
 #include <cstdlib>
 #include <dlfcn.h>
 #include <filesystem>
-#include <map>
 #include <sstream>
 
 namespace podio {
diff --git a/src/SIOFrameData.cc b/src/SIOFrameData.cc
index 806639672..e542417bc 100644
--- a/src/SIOFrameData.cc
+++ b/src/SIOFrameData.cc
@@ -1,6 +1,6 @@
 #include "podio/SIOFrameData.h"
-#include "podio/SIOBlock.h"
 
+#include "podio/SIOBlock.h"
 #include <sio/compression/zlib.h>
 
 #include <algorithm>
diff --git a/src/SIOLegacyReader.cc b/src/SIOLegacyReader.cc
index dcf3d9d18..2c54e51e5 100644
--- a/src/SIOLegacyReader.cc
+++ b/src/SIOLegacyReader.cc
@@ -1,7 +1,6 @@
 #include "podio/SIOLegacyReader.h"
 
 #include "sioUtils.h"
-
 #include <sio/api.h>
 #include <sio/compression/zlib.h>
 #include <sio/definitions.h>
diff --git a/src/SIOReader.cc b/src/SIOReader.cc
index 2609d611f..c2304e870 100644
--- a/src/SIOReader.cc
+++ b/src/SIOReader.cc
@@ -1,7 +1,6 @@
 #include "podio/SIOReader.h"
 
 #include "sioUtils.h"
-
 #include <sio/api.h>
 #include <sio/definitions.h>
 
diff --git a/src/SIOWriter.cc b/src/SIOWriter.cc
index aef6e52e6..6db167034 100644
--- a/src/SIOWriter.cc
+++ b/src/SIOWriter.cc
@@ -1,7 +1,7 @@
 #include "podio/SIOWriter.h"
+
 #include "podio/Frame.h"
 #include "podio/SIOBlock.h"
-
 #include "sioUtils.h"
 
 #include <memory>
diff --git a/src/SchemaEvolution.cc b/src/SchemaEvolution.cc
index 4576cde1e..a12622a9b 100644
--- a/src/SchemaEvolution.cc
+++ b/src/SchemaEvolution.cc
@@ -1,7 +1,10 @@
 #include "podio/SchemaEvolution.h"
+
 #include "podio/CollectionBuffers.h"
 
 #include <iostream>
+#include <tuple>
+#include <utility>
 
 namespace podio {
 
diff --git a/src/UserDataCollection.cc b/src/UserDataCollection.cc
index 673e7969c..dfbf1c85e 100644
--- a/src/UserDataCollection.cc
+++ b/src/UserDataCollection.cc
@@ -1,9 +1,13 @@
 #include "podio/UserDataCollection.h"
+
 #include "podio/CollectionBufferFactory.h"
 #include "podio/CollectionBuffers.h"
 #include "podio/SchemaEvolution.h"
 
+#include <memory>
+#include <ostream>
 #include <tuple>
+#include <utility>
 #include <vector>
 
 namespace podio {
diff --git a/src/Writer.cc b/src/Writer.cc
index 13f979ce8..740a79979 100644
--- a/src/Writer.cc
+++ b/src/Writer.cc
@@ -8,7 +8,11 @@
   #include "podio/SIOWriter.h"
 #endif
 
+#include <algorithm>
+#include <cctype>
 #include <memory>
+#include <stdexcept>
+#include <utility>
 
 namespace podio {
 
diff --git a/src/rootUtils.h b/src/rootUtils.h
index a473c6f0c..774bc6f3a 100644
--- a/src/rootUtils.h
+++ b/src/rootUtils.h
@@ -1,11 +1,10 @@
 #ifndef PODIO_ROOT_UTILS_H // NOLINT(llvm-header-guard): internal headers confuse clang-tidy
 #define PODIO_ROOT_UTILS_H // NOLINT(llvm-header-guard): internal headers confuse clang-tidy
 
-#include "podio/CollectionIDTable.h"
-#include "podio/utilities/RootHelpers.h"
-
 #include "TBranch.h"
 #include "TTree.h"
+#include "podio/CollectionIDTable.h"
+#include "podio/utilities/RootHelpers.h"
 
 #include <algorithm>
 #include <cctype>
diff --git a/src/sioUtils.h b/src/sioUtils.h
index 352a338b6..073aabf5c 100644
--- a/src/sioUtils.h
+++ b/src/sioUtils.h
@@ -4,7 +4,6 @@
 #include "podio/CollectionBase.h"
 #include "podio/GenericParameters.h"
 #include "podio/SIOBlock.h"
-
 #include <sio/api.h>
 #include <sio/compression/zlib.h>
 #include <sio/definitions.h>
diff --git a/src/test_hashes.cpp b/src/test_hashes.cpp
index bcceafa56..7ca7cbcaf 100644
--- a/src/test_hashes.cpp
+++ b/src/test_hashes.cpp
@@ -1,11 +1,14 @@
 #include "MurmurHash3.h"
 
+#include <cstddef>
+#include <cstdint>
 #include <fstream>
 #include <iomanip>
 #include <iostream>
 #include <iterator>
 #include <map>
 #include <string>
+#include <tuple>
 #include <utility>
 #include <vector>
 
diff --git a/tests/read_frame.h b/tests/read_frame.h
index 0103afea1..06e50394c 100644
--- a/tests/read_frame.h
+++ b/tests/read_frame.h
@@ -3,13 +3,11 @@
 
 #include "datamodel/ExampleWithInterfaceRelationCollection.h"
 #include "datamodel/ExampleWithVectorMemberCollection.h"
-#include "read_test.h"
-
 #include "extension_model/ContainedTypeCollection.h"
 #include "extension_model/ExternalComponentTypeCollection.h"
 #include "extension_model/ExternalRelationTypeCollection.h"
-
 #include "podio/Frame.h"
+#include "read_test.h"
 
 #include <iostream>
 
diff --git a/tests/read_frame_auxiliary.h b/tests/read_frame_auxiliary.h
index 65bffad28..c755eed42 100644
--- a/tests/read_frame_auxiliary.h
+++ b/tests/read_frame_auxiliary.h
@@ -2,7 +2,6 @@
 #define PODIO_TESTS_READ_FRAME_AUXILIARY_H // NOLINT(llvm-header-guard): folder structure not suitable
 
 #include "frame_test_common.h"
-
 #include "podio/Frame.h"
 #include "podio/podioVersion.h"
 
diff --git a/tests/read_interface.h b/tests/read_interface.h
index 278e03742..3ec3d892d 100644
--- a/tests/read_interface.h
+++ b/tests/read_interface.h
@@ -1,9 +1,8 @@
 #ifndef PODIO_TESTS_READ_INTERFACE_H // NOLINT(llvm-header-guard): folder structure not suitable
 #define PODIO_TESTS_READ_INTERFACE_H // NOLINT(llvm-header-guard): folder structure not suitable
 
-#include "read_frame.h"
-
 #include "podio/Reader.h"
+#include "read_frame.h"
 
 int read_frames(podio::Reader& reader) {
 
diff --git a/tests/read_python_frame.h b/tests/read_python_frame.h
index 5c3220708..6cb1f02d3 100644
--- a/tests/read_python_frame.h
+++ b/tests/read_python_frame.h
@@ -3,7 +3,6 @@
 
 #include "datamodel/ExampleClusterCollection.h"
 #include "datamodel/ExampleHitCollection.h"
-
 #include "podio/Frame.h"
 
 #include <iostream>
diff --git a/tests/root_io/read_and_write_associated.cpp b/tests/root_io/read_and_write_associated.cpp
index 9cf005c96..a9ddffbd8 100644
--- a/tests/root_io/read_and_write_associated.cpp
+++ b/tests/root_io/read_and_write_associated.cpp
@@ -1,13 +1,22 @@
-#include "podio/Frame.h"
-#include "podio/ROOTReader.h"
-#include "podio/ROOTWriter.h"
-
 #include "datamodel/EventInfoCollection.h"
+#include "datamodel/ExampleCluster.h"
 #include "datamodel/ExampleClusterCollection.h"
+#include "datamodel/ExampleHit.h"
 #include "datamodel/ExampleHitCollection.h"
+#include "datamodel/MutableEventInfo.h"
+#include "datamodel/MutableExampleCluster.h"
+#include "datamodel/MutableExampleHit.h"
+#include "podio/Frame.h"
+#include "podio/FrameCategories.h"
+#include "podio/ROOTReader.h"
+#include "podio/ROOTWriter.h"
+#include "podio/RelationRange.h"
 
 #include <iostream>
+#include <stdexcept>
 #include <string>
+#include <utility>
+#include <vector>
 
 void writeCollection() {
   podio::ROOTWriter writer("associations.root");
diff --git a/tests/root_io/read_and_write_frame_root.cpp b/tests/root_io/read_and_write_frame_root.cpp
index 7cde787b2..e38ff0e5f 100644
--- a/tests/root_io/read_and_write_frame_root.cpp
+++ b/tests/root_io/read_and_write_frame_root.cpp
@@ -1,7 +1,6 @@
-#include "read_and_write_frame.h"
-
 #include "podio/ROOTReader.h"
 #include "podio/ROOTWriter.h"
+#include "read_and_write_frame.h"
 
 int main() {
   return rewrite_frames<podio::ROOTReader, podio::ROOTWriter>("example_frame.root", "rewritten_frame.root") +
diff --git a/tests/root_io/read_frame_legacy_root.cpp b/tests/root_io/read_frame_legacy_root.cpp
index 6d98f79ac..0c1b8d82e 100644
--- a/tests/root_io/read_frame_legacy_root.cpp
+++ b/tests/root_io/read_frame_legacy_root.cpp
@@ -1,9 +1,11 @@
-#include "read_test.h"
-
 #include "podio/Frame.h"
 #include "podio/ROOTLegacyReader.h"
+#include "read_test.h"
 
+#include <cstddef>
 #include <iostream>
+#include <stdexcept>
+#include <string>
 
 int main(int argc, char* argv[]) {
   if (argc != 2) {
diff --git a/tests/root_io/read_frame_root.cpp b/tests/root_io/read_frame_root.cpp
index 40f8cdccf..71d8a34b3 100644
--- a/tests/root_io/read_frame_root.cpp
+++ b/tests/root_io/read_frame_root.cpp
@@ -1,8 +1,7 @@
+#include "podio/ROOTReader.h"
 #include "read_frame.h"
 #include "read_frame_auxiliary.h"
 
-#include "podio/ROOTReader.h"
-
 #include <iostream>
 #include <string>
 
diff --git a/tests/root_io/read_frame_root_multiple.cpp b/tests/root_io/read_frame_root_multiple.cpp
index 7c76e25ef..ba579a9c5 100644
--- a/tests/root_io/read_frame_root_multiple.cpp
+++ b/tests/root_io/read_frame_root_multiple.cpp
@@ -1,6 +1,14 @@
+#include "podio/Frame.h"
+#include "podio/ROOTReader.h"
+#include "podio/podioVersion.h"
 #include "read_frame.h"
+#include "read_test.h"
 
-#include "podio/ROOTReader.h"
+#include <cstddef>
+#include <iostream>
+#include <memory>
+#include <string>
+#include <vector>
 
 int read_frames(podio::ROOTReader& reader) {
   if (reader.currentFileVersion() != podio::version::build_version) {
diff --git a/tests/root_io/read_interface_rntuple.cpp b/tests/root_io/read_interface_rntuple.cpp
index e2ee2a421..0aabee632 100644
--- a/tests/root_io/read_interface_rntuple.cpp
+++ b/tests/root_io/read_interface_rntuple.cpp
@@ -1,3 +1,4 @@
+#include "podio/Reader.h"
 #include "read_interface.h"
 
 int main(int, char**) {
diff --git a/tests/root_io/read_interface_root.cpp b/tests/root_io/read_interface_root.cpp
index 8d33ec1c3..707c698a7 100644
--- a/tests/root_io/read_interface_root.cpp
+++ b/tests/root_io/read_interface_root.cpp
@@ -1,3 +1,4 @@
+#include "podio/Reader.h"
 #include "read_interface.h"
 
 int main(int, char**) {
diff --git a/tests/root_io/read_python_frame_rntuple.cpp b/tests/root_io/read_python_frame_rntuple.cpp
index 0d21563d4..2fda6418b 100644
--- a/tests/root_io/read_python_frame_rntuple.cpp
+++ b/tests/root_io/read_python_frame_rntuple.cpp
@@ -1,6 +1,5 @@
-#include "read_python_frame.h"
-
 #include "podio/RNTupleReader.h"
+#include "read_python_frame.h"
 
 int main() {
   return read_frame<podio::RNTupleReader>("example_frame_with_py_rntuple.root");
diff --git a/tests/root_io/read_python_frame_root.cpp b/tests/root_io/read_python_frame_root.cpp
index a3497831d..c4dd74726 100644
--- a/tests/root_io/read_python_frame_root.cpp
+++ b/tests/root_io/read_python_frame_root.cpp
@@ -1,6 +1,5 @@
-#include "read_python_frame.h"
-
 #include "podio/ROOTReader.h"
+#include "read_python_frame.h"
 
 int main() {
   return read_frame<podio::ROOTReader>("example_frame_with_py.root");
diff --git a/tests/root_io/relation_range.cpp b/tests/root_io/relation_range.cpp
index 6159e8cdc..59532b156 100644
--- a/tests/root_io/relation_range.cpp
+++ b/tests/root_io/relation_range.cpp
@@ -1,14 +1,21 @@
+#include "datamodel/ExampleMC.h"
 #include "datamodel/ExampleMCCollection.h"
+#include "datamodel/ExampleReferencingType.h"
+#include "datamodel/MutableExampleMC.h"
 #include "datamodel/MutableExampleReferencingType.h"
 #include "datamodel/MutableExampleWithVectorMember.h"
-
 #include "podio/Frame.h"
+#include "podio/FrameCategories.h"
 #include "podio/ROOTReader.h"
 #include "podio/ROOTWriter.h"
+#include "podio/RelationRange.h"
 
+#include <cstddef>
+#include <iostream>
 #include <sstream>
 #include <stdexcept>
 #include <string>
+#include <utility>
 #include <vector>
 
 #define LOCATION()                                                                                                     \
diff --git a/tests/root_io/write_frame_root.cpp b/tests/root_io/write_frame_root.cpp
index 2ad648e36..646d85386 100644
--- a/tests/root_io/write_frame_root.cpp
+++ b/tests/root_io/write_frame_root.cpp
@@ -1,6 +1,5 @@
-#include "write_frame.h"
-
 #include "podio/ROOTWriter.h"
+#include "write_frame.h"
 
 int main(int, char**) {
   write_frames<podio::ROOTWriter>("example_frame.root");
diff --git a/tests/root_io/write_interface_rntuple.cpp b/tests/root_io/write_interface_rntuple.cpp
index c13658c61..5fab04b3b 100644
--- a/tests/root_io/write_interface_rntuple.cpp
+++ b/tests/root_io/write_interface_rntuple.cpp
@@ -1,3 +1,4 @@
+#include "podio/Writer.h"
 #include "write_interface.h"
 
 int main(int, char**) {
diff --git a/tests/root_io/write_interface_root.cpp b/tests/root_io/write_interface_root.cpp
index 84775e6de..2c9c5900e 100644
--- a/tests/root_io/write_interface_root.cpp
+++ b/tests/root_io/write_interface_root.cpp
@@ -1,3 +1,4 @@
+#include "podio/Writer.h"
 #include "write_interface.h"
 
 int main(int, char**) {
diff --git a/tests/schema_evolution/read_new_data.h b/tests/schema_evolution/read_new_data.h
index cdc3abf46..7805c48aa 100644
--- a/tests/schema_evolution/read_new_data.h
+++ b/tests/schema_evolution/read_new_data.h
@@ -5,7 +5,6 @@
 #include "datamodel/ExampleWithARelationCollection.h"
 #include "datamodel/ExampleWithArrayComponentCollection.h"
 #include "datamodel/ExampleWithNamespaceCollection.h"
-
 #include "podio/Frame.h"
 
 #include <iostream>
diff --git a/tests/schema_evolution/root_io/read_new_data_root.cpp b/tests/schema_evolution/root_io/read_new_data_root.cpp
index b69306478..388075ee2 100644
--- a/tests/schema_evolution/root_io/read_new_data_root.cpp
+++ b/tests/schema_evolution/root_io/read_new_data_root.cpp
@@ -1,6 +1,5 @@
-#include "read_new_data.h"
-
 #include "podio/ROOTReader.h"
+#include "read_new_data.h"
 
 int main() {
   return read_new_data<podio::ROOTReader>("example_data_old_schema.root");
diff --git a/tests/schema_evolution/root_io/write_old_data_root.cpp b/tests/schema_evolution/root_io/write_old_data_root.cpp
index dcd971d08..3ca010a75 100644
--- a/tests/schema_evolution/root_io/write_old_data_root.cpp
+++ b/tests/schema_evolution/root_io/write_old_data_root.cpp
@@ -1,6 +1,5 @@
-#include "schema_evolution/write_old_data.h"
-
 #include "podio/ROOTWriter.h"
+#include "schema_evolution/write_old_data.h"
 
 int main() {
   return writeData<podio::ROOTWriter>("example_data_old_schema.root");
diff --git a/tests/schema_evolution/write_old_data.h b/tests/schema_evolution/write_old_data.h
index 7676ae34b..9f0780b78 100644
--- a/tests/schema_evolution/write_old_data.h
+++ b/tests/schema_evolution/write_old_data.h
@@ -5,7 +5,6 @@
 #include "datamodel/ExampleWithARelationCollection.h"
 #include "datamodel/ExampleWithArrayComponentCollection.h"
 #include "datamodel/ExampleWithNamespaceCollection.h"
-
 #include "podio/Frame.h"
 
 #include <string>
diff --git a/tests/sio_io/read_and_write_frame_sio.cpp b/tests/sio_io/read_and_write_frame_sio.cpp
index 003d80ea4..edb233a08 100644
--- a/tests/sio_io/read_and_write_frame_sio.cpp
+++ b/tests/sio_io/read_and_write_frame_sio.cpp
@@ -1,7 +1,6 @@
-#include "read_and_write_frame.h"
-
 #include "podio/SIOReader.h"
 #include "podio/SIOWriter.h"
+#include "read_and_write_frame.h"
 
 int main() {
   return rewrite_frames<podio::SIOReader, podio::SIOWriter>("example_frame.sio", "rewritten_frame.sio") +
diff --git a/tests/sio_io/read_frame_legacy_sio.cpp b/tests/sio_io/read_frame_legacy_sio.cpp
index 5dbc123d3..2414462c3 100644
--- a/tests/sio_io/read_frame_legacy_sio.cpp
+++ b/tests/sio_io/read_frame_legacy_sio.cpp
@@ -1,7 +1,6 @@
-#include "read_test.h"
-
 #include "podio/Frame.h"
 #include "podio/SIOLegacyReader.h"
+#include "read_test.h"
 
 #include <iostream>
 
diff --git a/tests/sio_io/read_frame_sio.cpp b/tests/sio_io/read_frame_sio.cpp
index 8a27743ac..0b500af2f 100644
--- a/tests/sio_io/read_frame_sio.cpp
+++ b/tests/sio_io/read_frame_sio.cpp
@@ -1,8 +1,7 @@
+#include "podio/SIOReader.h"
 #include "read_frame.h"
 #include "read_frame_auxiliary.h"
 
-#include "podio/SIOReader.h"
-
 int main(int argc, char* argv[]) {
   std::string inputFile = "example_frame.sio";
   bool assertBuildVersion = true;
diff --git a/tests/sio_io/read_python_frame_sio.cpp b/tests/sio_io/read_python_frame_sio.cpp
index 5307c1038..d3c5834e1 100644
--- a/tests/sio_io/read_python_frame_sio.cpp
+++ b/tests/sio_io/read_python_frame_sio.cpp
@@ -1,6 +1,5 @@
-#include "read_python_frame.h"
-
 #include "podio/SIOReader.h"
+#include "read_python_frame.h"
 
 int main() {
   return read_frame<podio::SIOReader>("example_frame_with_py.sio");
diff --git a/tests/sio_io/write_frame_sio.cpp b/tests/sio_io/write_frame_sio.cpp
index 21cd740ca..10bdcbcef 100644
--- a/tests/sio_io/write_frame_sio.cpp
+++ b/tests/sio_io/write_frame_sio.cpp
@@ -1,6 +1,5 @@
-#include "write_frame.h"
-
 #include "podio/SIOWriter.h"
+#include "write_frame.h"
 
 int main(int, char**) {
   write_frames<podio::SIOWriter>("example_frame.sio");
diff --git a/tests/unittests/buffer_factory.cpp b/tests/unittests/buffer_factory.cpp
index d97c09bd0..dea1aaa1d 100644
--- a/tests/unittests/buffer_factory.cpp
+++ b/tests/unittests/buffer_factory.cpp
@@ -1,11 +1,19 @@
-#include "datamodel/ExampleHitCollectionData.h"
-#include "podio/CollectionBufferFactory.h"
-
+#include "catch2/catch_test_macros.hpp"
 #include "datamodel/DatamodelDefinition.h"
 #include "datamodel/ExampleClusterCollection.h"
-#include "datamodel/ExampleWithVectorMemberCollection.h"
+#include "datamodel/ExampleClusterCollectionData.h"
+#include "datamodel/ExampleClusterData.h"
+#include "datamodel/ExampleHitCollectionData.h"
+#include "datamodel/ExampleHitData.h"
+#include "datamodel/ExampleWithVectorMemberCollectionData.h"
+#include "podio/CollectionBufferFactory.h"
+#include "podio/CollectionBuffers.h"
+#include "podio/ObjectID.h"
 
-#include "catch2/catch_test_macros.hpp"
+#include <memory>
+#include <optional>
+#include <utility>
+#include <vector>
 
 TEST_CASE("createBuffers", "[internals][memory-management]") {
   const auto& factory = podio::CollectionBufferFactory::instance();
diff --git a/tests/unittests/frame.cpp b/tests/unittests/frame.cpp
index ac014a898..1edd5f31b 100644
--- a/tests/unittests/frame.cpp
+++ b/tests/unittests/frame.cpp
@@ -1,11 +1,19 @@
 #include "podio/Frame.h"
 
 #include "catch2/catch_test_macros.hpp"
-
+#include "datamodel/ExampleCluster.h"
 #include "datamodel/ExampleClusterCollection.h"
+#include "datamodel/ExampleHit.h"
 #include "datamodel/ExampleHitCollection.h"
+#include "datamodel/MutableExampleCluster.h"
+#include "podio/RelationRange.h"
 
+#include <algorithm>
+#include <array>
+#include <initializer_list>
 #include <map>
+#include <optional>
+#include <stdexcept>
 #include <string>
 #include <thread>
 #include <utility>
diff --git a/tests/unittests/interface_types.cpp b/tests/unittests/interface_types.cpp
index a98b55b5d..9978bc0a0 100644
--- a/tests/unittests/interface_types.cpp
+++ b/tests/unittests/interface_types.cpp
@@ -1,10 +1,11 @@
 #include "catch2/catch_test_macros.hpp"
-
-#include "podio/ObjectID.h"
-
+#include "datamodel/ExampleCluster.h"
+#include "datamodel/ExampleHit.h"
 #include "datamodel/ExampleHitCollection.h"
 #include "datamodel/MutableExampleCluster.h"
+#include "datamodel/MutableExampleHit.h"
 #include "datamodel/TypeWithEnergy.h"
+#include "podio/ObjectID.h"
 
 #include <map>
 #include <stdexcept>
diff --git a/tests/unittests/std_interoperability.cpp b/tests/unittests/std_interoperability.cpp
index b0a97843a..6c6241faa 100644
--- a/tests/unittests/std_interoperability.cpp
+++ b/tests/unittests/std_interoperability.cpp
@@ -2,11 +2,13 @@
 #include "datamodel/ExampleHitCollection.h"
 #include "datamodel/MutableExampleHit.h"
 #include <catch2/catch_test_macros.hpp>
+
 #include <iterator>
 #include <limits>
 #include <memory>
 #include <stdexcept>
 #include <type_traits>
+#include <utility>
 
 // DOCUMENTED_STATIC_FAILURE and DOCUMENTED_FAILURE macro are used to indicate checks that corresponds to requirements
 // imposed but the standard but currently not met by podio. These check use inverted logic (they pass when the
diff --git a/tests/unittests/unittest.cpp b/tests/unittests/unittest.cpp
index 733e42854..e5e486944 100644
--- a/tests/unittests/unittest.cpp
+++ b/tests/unittests/unittest.cpp
@@ -1,23 +1,56 @@
 // STL
+#include "catch2/catch_test_macros.hpp"
+#include "catch2/matchers/catch_matchers_string.hpp"
+#include "catch2/matchers/catch_matchers_vector.hpp"
+#include <catch2/matchers/catch_matchers.hpp>
+#include <nlohmann/json_fwd.hpp>
+
+#include <array>
+#include <compare>
+#include <cstddef>
 #include <cstdint>
 #include <filesystem>
+#include <iostream>
 #include <map>
+#include <memory>
+#include <optional>
+#include <set>
 #include <sstream>
 #include <stdexcept>
+#include <string>
 #include <thread>
+#include <tuple>
 #include <type_traits>
+#include <utility>
 #include <vector>
-
-#include "catch2/catch_test_macros.hpp"
-#include "catch2/matchers/catch_matchers_string.hpp"
-#include "catch2/matchers/catch_matchers_vector.hpp"
-
 // podio specific includes
+#include "datamodel/CompWithInit.h"
+#include "datamodel/ExampleCluster.h"
+#include "datamodel/ExampleForCyclicDependency1.h"
+#include "datamodel/ExampleForCyclicDependency2.h"
+#include "datamodel/ExampleHit.h"
+#include "datamodel/ExampleHitData.h"
+#include "datamodel/ExampleWithOneRelation.h"
+#include "datamodel/ExampleWithVectorMember.h"
+#include "datamodel/MutableEventInfo.h"
+#include "datamodel/MutableExampleForCyclicDependency1.h"
+#include "datamodel/MutableExampleForCyclicDependency2.h"
+#include "datamodel/MutableExampleHit.h"
+#include "datamodel/MutableExampleWithOneRelation.h"
+#include "datamodel/MutableExampleWithUserInit.h"
+#include "datamodel/MutableExampleWithVectorMember.h"
+#include "datamodel/NamespaceStruct.h"
+#include "datamodel/NotSoSimpleStruct.h"
+#include "datamodel/SimpleStruct.h"
+#include "podio/CollectionBuffers.h"
 #include "podio/Frame.h"
+#include "podio/FrameCategories.h"
 #include "podio/GenericParameters.h"
+#include "podio/ObjectID.h"
 #include "podio/ROOTLegacyReader.h"
 #include "podio/ROOTReader.h"
 #include "podio/ROOTWriter.h"
+#include "podio/RelationRange.h"
 #include "podio/podioVersion.h"
 
 #ifndef PODIO_ENABLE_SIO
@@ -42,7 +75,6 @@
 #include "datamodel/ExampleHitCollection.h"
 #include "datamodel/ExampleWithArray.h"
 #include "datamodel/ExampleWithArrayComponent.h"
-#include "datamodel/ExampleWithComponent.h"
 #include "datamodel/ExampleWithExternalExtraCode.h"
 #include "datamodel/ExampleWithFixedWidthIntegers.h"
 #include "datamodel/ExampleWithOneRelationCollection.h"
@@ -53,7 +85,6 @@
 #include "datamodel/MutableExampleWithComponent.h"
 #include "datamodel/MutableExampleWithExternalExtraCode.h"
 #include "datamodel/StructWithExtraCode.h"
-
 #include "podio/UserDataCollection.h"
 
 TEST_CASE("AutoDelete", "[basics][memory-management]") {
@@ -794,9 +825,6 @@ void checkCollections(/*const*/ ExampleHitCollection& hits, /*const*/ ExampleClu
   }
 }
 
-template <typename>
-struct TD;
-
 TEST_CASE("Move-only collections", "[collections][move-semantics]") {
   // Setup a few collections that will be used throughout below
   auto [hitColl, clusterColl, vecMemColl, userDataColl] = createCollections();
diff --git a/tests/write_frame.h b/tests/write_frame.h
index 1e1c9f966..d5ab77543 100644
--- a/tests/write_frame.h
+++ b/tests/write_frame.h
@@ -1,8 +1,6 @@
 #ifndef PODIO_TESTS_WRITE_FRAME_H // NOLINT(llvm-header-guard): folder structure not suitable
 #define PODIO_TESTS_WRITE_FRAME_H // NOLINT(llvm-header-guard): folder structure not suitable
 
-#include "frame_test_common.h"
-
 #include "datamodel/EventInfoCollection.h"
 #include "datamodel/ExampleClusterCollection.h"
 #include "datamodel/ExampleHitCollection.h"
@@ -15,11 +13,10 @@
 #include "datamodel/ExampleWithNamespaceCollection.h"
 #include "datamodel/ExampleWithOneRelationCollection.h"
 #include "datamodel/ExampleWithVectorMemberCollection.h"
-
 #include "extension_model/ContainedTypeCollection.h"
 #include "extension_model/ExternalComponentTypeCollection.h"
 #include "extension_model/ExternalRelationTypeCollection.h"
-
+#include "frame_test_common.h"
 #include "podio/Frame.h"
 #include "podio/UserDataCollection.h"
 
diff --git a/tests/write_interface.h b/tests/write_interface.h
index 1acaa2383..484395098 100644
--- a/tests/write_interface.h
+++ b/tests/write_interface.h
@@ -1,9 +1,8 @@
 #ifndef PODIO_TESTS_WRITE_INTERFACE_H // NOLINT(llvm-header-guard): folder structure not suitable
 #define PODIO_TESTS_WRITE_INTERFACE_H // NOLINT(llvm-header-guard): folder structure not suitable
 
-#include "write_frame.h"
-
 #include "podio/Writer.h"
+#include "write_frame.h"
 
 void write_frames(podio::Writer& frameWriter) {