diff --git a/CMakeLists.txt b/CMakeLists.txt
index de79677..ff3c464 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -114,7 +114,10 @@ elseif(${IS_CLANG})
     if (CMAKE_CXX_COMPILER_VERSION VERSION_LESS ${MINIMAL_CLANG} AND NOT ${IGNORE_MINIMAL_COMPILER_VERSION})
         message(FATAL_ERROR "Clang ${MINIMAL_CLANG} or higher is required.")
     endif()
-    if (${CMAKE_INTERPROCEDURAL_OPTIMIZATION_RELEASE} OR (MINGW AND NOT USER_DEFINED_INTERPROCEDURAL_OPTIMIZATION_RELEASE)) # CMAKE_INTERPROCEDURAL_OPTIMIZATION_RELEASE is false on llvm-mingw toolchains even though it is supported
+    if (MINGW AND NOT USER_DEFINED_INTERPROCEDURAL_OPTIMIZATION_RELEASE) # CMAKE_INTERPROCEDURAL_OPTIMIZATION_RELEASE is false on llvm-mingw toolchains even though it is supported
+        set(CMAKE_INTERPROCEDURAL_OPTIMIZATION_RELEASE YES)
+    endif()
+    if (CMAKE_INTERPROCEDURAL_OPTIMIZATION_RELEASE)
         set(CMAKE_CXX_FLAGS_RELEASE "${CMAKE_CXX_FLAGS_RELEASE} -flto=thin")
         if (NOT DEFINED EMSCRIPTEN)
             set(CMAKE_CXX_FLAGS_RELEASE "${CMAKE_CXX_FLAGS_RELEASE} -fwhole-program-vtables")