diff --git a/src/match_entry.c b/src/match_entry.c
index 7c441a0..a3b4fa5 100644
--- a/src/match_entry.c
+++ b/src/match_entry.c
@@ -8,6 +8,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include <pcre.h>
+#include <assert.h>
 #include <stdbool.h>
 
 #include "r3.h"