diff --git a/src/sentinel.c b/src/sentinel.c
index 5be4193dc..5bd594955 100644
--- a/src/sentinel.c
+++ b/src/sentinel.c
@@ -2218,8 +2218,8 @@ void sentinelRefreshInstanceInfo(sentinelRedisInstance *ri, const char *info) {
         }
 
         /* role:<role> */
-        if (!memcmp(l,"role:master",11)) role = SRI_MASTER;
-        else if (!memcmp(l,"role:slave",10)) role = SRI_SLAVE;
+        if (sdslen(l) >= 11 && !memcmp(l,"role:master",11)) role = SRI_MASTER;
+        else if (sdslen(l) >= 10 && !memcmp(l,"role:slave",10)) role = SRI_SLAVE;
 
         if (role == SRI_SLAVE) {
             /* master_host:<host> */