diff --git a/src/util.c b/src/util.c
index 5437ad6..64c3be9 100644
--- a/src/util.c
+++ b/src/util.c
@@ -1,5 +1,6 @@
 #include "minitar.h"
 #include "tar.h"
+#include <assert.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -93,6 +94,7 @@ static size_t minitar_align_down_to_block_size(size_t size)
 static char* minitar_static_dup(const char* str, size_t size)
 {
     static char result[1024];
+    assert(size < 1024);
     memcpy(result, str, size);
     result[size] = 0;
     return result;