diff --git a/test/src/unit-regression2.cpp b/test/src/unit-regression2.cpp
index 807e27f14..fb8b268c6 100644
--- a/test/src/unit-regression2.cpp
+++ b/test/src/unit-regression2.cpp
@@ -69,6 +69,7 @@ using ordered_json = nlohmann::ordered_json;
     #endif
 #endif
 
+#ifdef JSON_STD_FILESYSTEM_EXPERIMENTAL
 #if JSON_STD_FILESYSTEM_EXPERIMENTAL
 #include <experimental/filesystem>
 namespace nlohmann::detail
@@ -83,6 +84,7 @@ namespace std_fs = std::filesystem;
 } // namespace nlohmann::detail
 #endif
 #endif
+#endif
 
 #ifdef JSON_HAS_CPP_20
     #include <span>