diff --git a/src/libosmo-mgcp/mgcp_sdp.c b/src/libosmo-mgcp/mgcp_sdp.c
index 56fc611..01e7968 100644
--- a/src/libosmo-mgcp/mgcp_sdp.c
+++ b/src/libosmo-mgcp/mgcp_sdp.c
@@ -132,7 +132,7 @@
 	char *str_ptr;
 	char *pt_str;
 	char *pt_end;
-	unsigned int pt;
+	unsigned long int pt;
 	unsigned int count = 0;
 	unsigned int i;
 
@@ -163,6 +163,9 @@
 		    pt_str == pt_end)
 			goto error;
 
+		if (pt >> 7) /* PT is 7 bit field, higher values not allowed */
+			goto error;
+
 		/* Do not allow duplicate payload types */
 		for (i = 0; i < count; i++)
 			if (codecs[i].payload_type == pt)