diff --git a/common.h b/common.h
index 42fd915..5458639 100644
--- a/common.h
+++ b/common.h
@@ -7,6 +7,7 @@ You should have received a copy of the CC0 Public Domain Dedication along with t
 
 */
 #include <stdio.h>
+#include <assert.h>
 #include <string.h>
 #include <stdlib.h>
 #include <limits.h>