diff --git a/src/tool/mach-o-matic.cpp b/src/tool/mach-o-matic.cpp
index b498ed01f21..a7d8d0052b8 100644
--- a/src/tool/mach-o-matic.cpp
+++ b/src/tool/mach-o-matic.cpp
@@ -15,6 +15,7 @@
 #include <stdint.h>
 #include <string.h>
 #include <unistd.h>
+#include <assert.h>
 #include <stdio.h>
 #include <fcntl.h>