diff --git a/libasn1parser/asn1p_integer.c b/libasn1parser/asn1p_integer.c
index 98cfe08..2d06fb3 100644
--- a/libasn1parser/asn1p_integer.c
+++ b/libasn1parser/asn1p_integer.c
@@ -102,7 +102,7 @@
     static char static_buf[128];
     int ret = asn1p_itoa_s(static_buf, sizeof(static_buf), v);
     if(ret > 0) {
-        assert(ret < sizeof(static_buf));
+        assert((size_t)ret < sizeof(static_buf));
         return static_buf;
     } else {
         return NULL;