diff --git a/src/Translatable/Translatable.php b/src/Translatable/Translatable.php
index b1ea394..501419c 100644
--- a/src/Translatable/Translatable.php
+++ b/src/Translatable/Translatable.php
@@ -134,14 +134,10 @@ public function getTranslationModelNamespace()
     public function getRelationKey()
     {
         if ($this->translationForeignKey) {
-            $key = $this->translationForeignKey;
-        } elseif ($this->primaryKey !== 'id') {
-            $key = $this->primaryKey;
-        } else {
-            $key = $this->getForeignKey();
+            return $this->translationForeignKey;
         }
 
-        return $key;
+        return $this->getForeignKey();
     }
 
     /**