diff --git a/openbsc/src/libmgcp/mgcp_protocol.c b/openbsc/src/libmgcp/mgcp_protocol.c
index f22dd20..ccd15e8 100644
--- a/openbsc/src/libmgcp/mgcp_protocol.c
+++ b/openbsc/src/libmgcp/mgcp_protocol.c
@@ -309,7 +309,7 @@
 	return len;
 
 buffer_too_small:
-	LOGP(DMGCP, LOGL_ERROR, "SDP buffer too small: %zd (needed %d)\n",
+	LOGP(DMGCP, LOGL_ERROR, "SDP buffer too small: %zu (needed %d)\n",
 	     size, len);
 	return -1;
 }