diff --git a/build/apr_common.m4 b/build/apr_common.m4
index f4e2dfd..01d9a44 100644
--- build/apr_common.m4
+++ build/apr_common.m4
@@ -467,6 +467,7 @@ changequote([, ])dnl
 AC_MSG_CHECKING(size of $2)
 AC_CACHE_VAL(AC_CV_NAME,
 [AC_TRY_RUN([#include <stdio.h>
+#include <stdlib.h>
 $1
 #ifdef WIN32
 #define binmode "b"