diff --git a/library/think/Request.php b/library/think/Request.php
index 8a0dc80d..6a6e6b50 100644
--- a/library/think/Request.php
+++ b/library/think/Request.php
@@ -1353,7 +1353,7 @@ class Request
             $host = $this->server('HTTP_HOST');
         }
 
-        return true === $strict ? strstr($host, ':', true) : $host;
+        return true === $strict && strpos($host, ':') ? strstr($host, ':', true) : $host;
     }
 
     /**