diff --git a/mingw-w64-headers/include/mapidefs.h b/mingw-w64-headers/include/mapidefs.h
index 3fff962..39b195a 100644
--- a/mingw-w64-headers/include/mapidefs.h
+++ b/mingw-w64-headers/include/mapidefs.h
@@ -20,9 +20,7 @@
 #include <objbase.h>
 #endif
 
-#ifndef _INC_STDDEF
 #include <stddef.h>
-#endif
 
 #ifndef MAPI_DIM
 #define MAPI_DIM 1
diff --git a/mingw-w64-headers/include/wabdefs.h b/mingw-w64-headers/include/wabdefs.h
index 32d9167..4e61054 100644
--- a/mingw-w64-headers/include/wabdefs.h
+++ b/mingw-w64-headers/include/wabdefs.h
@@ -24,9 +24,7 @@
 #include <objbase.h>
 #endif
 
-#ifndef _INC_STDDEF
 #include <stddef.h>
-#endif
 
 #ifndef MAPI_DIM
 #define MAPI_DIM 1