diff --git a/tests/utils.h b/tests/utils.h
index f9d3d9b1..081c4cd9 100644
--- a/tests/utils.h
+++ b/tests/utils.h
@@ -19,6 +19,25 @@
 #ifndef __VKD3D_TEST_UTILS_H
 #define __VKD3D_TEST_UTILS_H
 
+/* Hack for MinGW-w64 headers.
+ *
+ * We want to use WIDL C inline wrappers because some methods
+ * in D3D12 interfaces return aggregate objects. Unfortunately,
+ * WIDL C inline wrappers are broken when used with MinGW-w64
+ * headers because FORCEINLINE expands to extern inline
+ * which leads to the "multiple storage classes in declaration
+ * specifiers" compiler error.
+ */
+#ifdef __MINGW32__
+# include <_mingw.h>
+# ifdef __MINGW64_VERSION_MAJOR
+#  undef __forceinline
+#  define __forceinline __inline__ __attribute__((__always_inline__,__gnu_inline__))
+# endif
+#endif
+
+#define COBJMACROS
+#define WIDL_C_INLINE_WRAPPERS
 #include <limits.h>
 #include <stdbool.h>
 #include <stdint.h>