diff --git a/include/nlohmann/detail/macro_scope.hpp b/include/nlohmann/detail/macro_scope.hpp
index 040e1b9a2..83d8e06b4 100644
--- a/include/nlohmann/detail/macro_scope.hpp
+++ b/include/nlohmann/detail/macro_scope.hpp
@@ -51,11 +51,11 @@
             #define JSON_HAS_EXPERIMENTAL_FILESYSTEM 1
         #endif
 
-        //// std::filesystem does not work on MinGW GCC 8: https://sourceforge.net/p/mingw-w64/bugs/737/
-        //#if defined(__MINGW32__) && defined(__GNUC__) && __GNUC__ == 8
-        //    #undef JSON_HAS_FILESYSTEM
-        //    #undef JSON_HAS_EXPERIMENTAL_FILESYSTEM
-        //#endif
+        // std::filesystem does not work on MinGW GCC 8: https://sourceforge.net/p/mingw-w64/bugs/737/
+        #if defined(__MINGW32__) && defined(__GNUC__) && __GNUC__ == 8
+            #undef JSON_HAS_FILESYSTEM
+            #undef JSON_HAS_EXPERIMENTAL_FILESYSTEM
+        #endif
     #endif
 #endif
 
diff --git a/single_include/nlohmann/json.hpp b/single_include/nlohmann/json.hpp
index 72be1389b..5be8bfa5d 100644
--- a/single_include/nlohmann/json.hpp
+++ b/single_include/nlohmann/json.hpp
@@ -2339,11 +2339,11 @@ using is_detected_convertible =
             #define JSON_HAS_EXPERIMENTAL_FILESYSTEM 1
         #endif
 
-        //// std::filesystem does not work on MinGW GCC 8: https://sourceforge.net/p/mingw-w64/bugs/737/
-        //#if defined(__MINGW32__) && defined(__GNUC__) && __GNUC__ == 8
-        //    #undef JSON_HAS_FILESYSTEM
-        //    #undef JSON_HAS_EXPERIMENTAL_FILESYSTEM
-        //#endif
+        // std::filesystem does not work on MinGW GCC 8: https://sourceforge.net/p/mingw-w64/bugs/737/
+        #if defined(__MINGW32__) && defined(__GNUC__) && __GNUC__ == 8
+            #undef JSON_HAS_FILESYSTEM
+            #undef JSON_HAS_EXPERIMENTAL_FILESYSTEM
+        #endif
     #endif
 #endif
 
diff --git a/test/CMakeLists.txt b/test/CMakeLists.txt
index 197fb11ee..0ab021051 100644
--- a/test/CMakeLists.txt
+++ b/test/CMakeLists.txt
@@ -59,9 +59,9 @@ foreach(feature ${CMAKE_CXX_COMPILE_FEATURES})
     endif()
 endforeach()
 # Clang only supports C++17 starting from Clang 5.0
-#if ("${CMAKE_CXX_COMPILER_ID}" MATCHES "Clang" AND CMAKE_CXX_COMPILER_VERSION VERSION_LESS 5.0)
-#    unset(compiler_supports_cpp_17)
-#endif()
+if ("${CMAKE_CXX_COMPILER_ID}" MATCHES "Clang" AND CMAKE_CXX_COMPILER_VERSION VERSION_LESS 5.0)
+    unset(compiler_supports_cpp_17)
+endif()
 
 file(GLOB files src/unit-*.cpp)
 
diff --git a/test/src/unit-regression2.cpp b/test/src/unit-regression2.cpp
index 5e0f8f804..22c0154d3 100644
--- a/test/src/unit-regression2.cpp
+++ b/test/src/unit-regression2.cpp
@@ -62,11 +62,11 @@ using ordered_json = nlohmann::ordered_json;
             #define JSON_HAS_EXPERIMENTAL_FILESYSTEM 1
         #endif
 
-        //// std::filesystem does not work on MinGW GCC 8: https://sourceforge.net/p/mingw-w64/bugs/737/
-        //#if defined(__MINGW32__) && defined(__GNUC__) && __GNUC__ == 8
-        //    #undef JSON_HAS_FILESYSTEM
-        //    #undef JSON_HAS_EXPERIMENTAL_FILESYSTEM
-        //#endif
+        // std::filesystem does not work on MinGW GCC 8: https://sourceforge.net/p/mingw-w64/bugs/737/
+        #if defined(__MINGW32__) && defined(__GNUC__) && __GNUC__ == 8
+            #undef JSON_HAS_FILESYSTEM
+            #undef JSON_HAS_EXPERIMENTAL_FILESYSTEM
+        #endif
     #endif
 #endif