diff --git a/external/chipmunk/src/cpCollision.c b/external/chipmunk/src/cpCollision.c
index e29e4bf82e..3474dc6700 100644
--- a/external/chipmunk/src/cpCollision.c
+++ b/external/chipmunk/src/cpCollision.c
@@ -22,6 +22,10 @@
 #include <stdio.h>
 #include <string.h>
 
+#ifndef WIN32
+#include <alloca.h>
+#endif
+
 #include "chipmunk_private.h"
 
 #if DEBUG && 0