diff --git a/PIL/Image.py b/PIL/Image.py
index 1e29db198..10f949778 100644
--- a/PIL/Image.py
+++ b/PIL/Image.py
@@ -1920,7 +1920,7 @@ def fromarray(obj, mode=None):
             mode, rawmode = _fromarray_typemap[typekey]
         except KeyError:
             # print typekey
-            raise TypeError("Cannot handle this data type")
+            raise TypeError("Cannot handle this data type %s" % repr(typekey))
     else:
         rawmode = mode
     if mode in ["1", "L", "I", "P", "F"]: