diff --git a/reactos/lib/comctl32/listview.c b/reactos/lib/comctl32/listview.c
index cfc92ed2e88..7cdb92cc58e 100644
--- a/reactos/lib/comctl32/listview.c
+++ b/reactos/lib/comctl32/listview.c
@@ -147,6 +147,7 @@
 #include <assert.h>
 #include <ctype.h>
 #include <string.h>
+#include <stddef.h>
 #include <stdlib.h>
 #include <stdarg.h>
 #include <stdio.h>
diff --git a/reactos/lib/ole32/oleproxy.c b/reactos/lib/ole32/oleproxy.c
index a2f63109a84..e381cde6574 100644
--- a/reactos/lib/ole32/oleproxy.c
+++ b/reactos/lib/ole32/oleproxy.c
@@ -35,6 +35,7 @@
 
 #include <stdlib.h>
 #include <stdarg.h>
+#include <stddef.h>
 #include <stdio.h>
 #include <string.h>