diff --git a/src/fmindex-collection/fmindex/VariableFMIndex.h b/src/fmindex-collection/fmindex/VariableFMIndex.h
index ac593504..5c345473 100644
--- a/src/fmindex-collection/fmindex/VariableFMIndex.h
+++ b/src/fmindex-collection/fmindex/VariableFMIndex.h
@@ -10,6 +10,8 @@
 #include "../search/Backtracking.h"
 #include "FMIndex.h"
 
+#include <string>
+#include <string_view>
 #include <variant>
 
 namespace fmindex_collection {