diff --git a/ext/xor_singleheader b/ext/xor_singleheader
index 5539876..14e12df 160000
--- a/ext/xor_singleheader
+++ b/ext/xor_singleheader
@@ -1 +1 @@
-Subproject commit 55398761ff07ff18596cb9b62c8d618fbe47ebdd
+Subproject commit 14e12dfa2dd94007e4f0edc1f606ed2a6a6e6599
diff --git a/include/binfuse/filter.hpp b/include/binfuse/filter.hpp
index e6da59b..c26e45e 100644
--- a/include/binfuse/filter.hpp
+++ b/include/binfuse/filter.hpp
@@ -113,7 +113,11 @@ class filter {
     return ftype<FilterType>::contains(needle, &fil_);
   }
 
-  [[nodiscard]] bool is_populated() const { return fil_.SegmentCount > 0; }
+  [[nodiscard]] std::size_t size() const {
+    return static_cast<std::size_t>(fil_.Size);
+  }
+
+  [[nodiscard]] bool is_populated() const { return size() > 0; }
 
   [[nodiscard]] std::size_t serialization_bytes() const {
     // upstream API should be const
diff --git a/include/binfuse/sharded_filter.hpp b/include/binfuse/sharded_filter.hpp
index 4c02d45..f0b5e5b 100644
--- a/include/binfuse/sharded_filter.hpp
+++ b/include/binfuse/sharded_filter.hpp
@@ -55,9 +55,9 @@ class sharded_filter : private sharded_mmap_base<AccessMode> {
   }
 
   [[nodiscard]] bool contains(std::uint64_t needle) const {
-    auto prefix = extract_prefix(needle);
+    const auto prefix = extract_prefix(needle);
     // we know prefix is always < max_shards() by definition
-    auto& filter = filters[prefix];
+    const auto& filter = filters[prefix];
     if (!filter.is_populated()) {
       // this filter has not been populated. no fingerprint pointer
       // has been set and an upstream `contain` call will throw
diff --git a/test/data/sharded_filter8_tiny.bin b/test/data/sharded_filter8_tiny.bin
index 216a9bf..30ea2db 100644
Binary files a/test/data/sharded_filter8_tiny.bin and b/test/data/sharded_filter8_tiny.bin differ
diff --git a/test/filter.cpp b/test/filter.cpp
index 0d96692..3720484 100644
--- a/test/filter.cpp
+++ b/test/filter.cpp
@@ -25,6 +25,7 @@ TEST(binfuse_filter, construct_from_upstream) { // NOLINT
 
   binfuse::filter8 filter(std::move(fil)); // NOLINT not trivial
   EXPECT_TRUE(filter.is_populated());
+  EXPECT_EQ(filter.size(), 3);
   EXPECT_TRUE(filter.contains(0x0000000000000000));
   EXPECT_TRUE(filter.contains(0x0000000000000001));
   EXPECT_TRUE(filter.contains(0x0000000000000002));