diff --git a/IPython/core/oinspect.py b/IPython/core/oinspect.py
index ef6a0d0..82a5666 100644
--- a/IPython/core/oinspect.py
+++ b/IPython/core/oinspect.py
@@ -416,6 +416,8 @@ class Inspector(Colorable):
 
         If any exception is generated, None is returned instead and the
         exception is suppressed."""
+        if not callable(obj):
+            return None        
         try:
             return _render_signature(signature(obj), oname)
         except: