diff --git a/openbsc/src/libtrau/rtp_proxy.c b/openbsc/src/libtrau/rtp_proxy.c
index 0074b4a..4278fc6 100644
--- a/openbsc/src/libtrau/rtp_proxy.c
+++ b/openbsc/src/libtrau/rtp_proxy.c
@@ -151,7 +151,7 @@
 		}
 	}
 	if (rtph->padding) {
-		if (payload_len < 0) {
+		if (payload_len < 1) {
 			DEBUGPC(DLMUX, "received RTP frame too short for "
 				"padding length\n");
 			return -EINVAL;