diff --git a/Modules/arraymodule.c b/Modules/arraymodule.c
index 4b89ad91536..0dfe4f61734 100644
--- a/Modules/arraymodule.c
+++ b/Modules/arraymodule.c
@@ -30,7 +30,11 @@ OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 #include "allobjects.h"
 #include "modsupport.h"
 #include "ceval.h"
+#ifdef STDC_HEADERS
+#include <stddef.h>
+#else
 #include <sys/types.h>		/* For size_t */
+#endif
 
 struct arrayobject; /* Forward */