diff --git a/include/types/server.h b/include/types/server.h
index 82eb55fdb..05d47835e 100644
--- a/include/types/server.h
+++ b/include/types/server.h
@@ -113,7 +113,7 @@ struct tree_occ {
 struct check {
 	struct connection *conn;		/* connection state for health checks */
 
-	short port;				/* the port to use for the health checks */
+	unsigned short port;			/* the port to use for the health checks */
 	struct buffer *bi, *bo;			/* input and output buffers to send/recv check */
 	struct task *task;			/* the task associated to the health check processing, NULL if disabled */
 	struct timeval start;			/* last health check start time */