diff --git a/src/Illuminate/Database/Eloquent/Relations/MorphTo.php b/src/Illuminate/Database/Eloquent/Relations/MorphTo.php
index 2f449876fac7..e21764131f72 100644
--- a/src/Illuminate/Database/Eloquent/Relations/MorphTo.php
+++ b/src/Illuminate/Database/Eloquent/Relations/MorphTo.php
@@ -164,7 +164,7 @@ protected function gatherKeysByType($type, $keyType)
                     ? array_keys($this->dictionary[$type])
                     : array_map(function ($modelId) {
                         return (string) $modelId;
-                    }, array_filter(array_keys($this->dictionary[$type])));
+                    }, array_keys($this->dictionary[$type]));
     }
 
     /**