diff --git a/Lib/fileinput.py b/Lib/fileinput.py
index a25a021..554beb2 100644
--- a/Lib/fileinput.py
+++ b/Lib/fileinput.py
@@ -225,10 +225,11 @@
             raise ValueError("FileInput opening mode must be one of "
                              "'r', 'rU', 'U' and 'rb'")
         self._mode = mode
-        if inplace and openhook:
-            raise ValueError("FileInput cannot use an opening hook in inplace mode")
-        elif openhook and not hasattr(openhook, '__call__'):
-            raise ValueError("FileInput openhook must be callable")
+        if openhook:
+            if inplace:
+                raise ValueError("FileInput cannot use an opening hook in inplace mode")
+            if not callable(openhook):
+                raise ValueError("FileInput openhook must be callable")
         self._openhook = openhook
 
     def __del__(self):