diff --git a/ringbuf.c b/ringbuf.c
index ffc979e..dc2078f 100644
--- a/ringbuf.c
+++ b/ringbuf.c
@@ -4,6 +4,7 @@
 // #include <string.h>
 
 #include "ringbuf.h"
+#include <assert.h>
 #include <stdint.h>
 
 #ifdef DEBUG