diff --git a/src/Relations/BelongsToThrough.php b/src/Relations/BelongsToThrough.php
index 924e870..09c0b41 100644
--- a/src/Relations/BelongsToThrough.php
+++ b/src/Relations/BelongsToThrough.php
@@ -335,9 +335,12 @@ public function getThroughParents()
      */
     public function getFirstForeignKeyName()
     {
-        /** @var \Illuminate\Database\Eloquent\Model $firstThroughParent */
         $firstThroughParent = end($this->throughParents);
 
+        if ($firstThroughParent === false) {
+            $firstThroughParent = $this->parent;
+        }
+
         return $this->prefix . $this->getForeignKeyName($firstThroughParent);
     }
 
@@ -348,9 +351,12 @@ public function getFirstForeignKeyName()
      */
     public function getQualifiedFirstLocalKeyName()
     {
-        /** @var \Illuminate\Database\Eloquent\Model $lastThroughParent */
         $lastThroughParent = end($this->throughParents);
 
+        if ($lastThroughParent === false) {
+            $lastThroughParent = $this->parent;
+        }
+
         return $lastThroughParent->qualifyColumn($this->getLocalKeyName($lastThroughParent));
     }