diff --git a/include/mgcp/mgcp.h b/include/mgcp/mgcp.h
index db05cc4..8271c7f 100644
--- a/include/mgcp/mgcp.h
+++ b/include/mgcp/mgcp.h
@@ -107,7 +107,7 @@
 	void *data;
 
 	struct mgcp_endpoint *endpoints;
-	unsigned int last_call_id;
+	uint32_t last_call_id;
 };
 
 /* config management */