diff --git a/src/Illuminate/Database/Query/Builder.php b/src/Illuminate/Database/Query/Builder.php
index b4da92901801..7c0e0a8547fb 100755
--- a/src/Illuminate/Database/Query/Builder.php
+++ b/src/Illuminate/Database/Query/Builder.php
@@ -342,24 +342,11 @@ protected function parseSub($query)
             return [$query, []];
         } else {
             throw new InvalidArgumentException(
-                'The subquery must be an instance of Closure or Builder, or a string.'
+                'A subquery must be a query builder instance, a Closure, or a string.'
             );
         }
     }
 
-    /**
-     * Determine if the value is a query builder instance or a closure.
-     *
-     * @param  mixed  $value
-     * @return bool
-     */
-    protected function isQueryable($value)
-    {
-        return $value instanceof self ||
-               $value instanceof EloquentBuilder ||
-               $value instanceof Closure;
-    }
-
     /**
      * Add a new select column to the query.
      *
@@ -2962,6 +2949,19 @@ public function useWritePdo()
         return $this;
     }
 
+    /**
+     * Determine if the value is a query builder instance or a Closure.
+     *
+     * @param  mixed  $value
+     * @return bool
+     */
+    protected function isQueryable($value)
+    {
+        return $value instanceof self ||
+               $value instanceof EloquentBuilder ||
+               $value instanceof Closure;
+    }
+
     /**
      * Clone the query without the given properties.
      *