diff --git a/keras/layers/merge.py b/keras/layers/merge.py
index d59aeeb6697..8c65f9feb46 100644
--- a/keras/layers/merge.py
+++ b/keras/layers/merge.py
@@ -330,9 +330,9 @@ def __init__(self, axis=-1, **kwargs):
 
     def build(self, input_shape):
         # Used purely for shape validation.
-        if not isinstance(input_shape, list):
+        if not isinstance(input_shape, list) or len(input_shape) < 2:
             raise ValueError('`Concatenate` layer should be called '
-                             'on a list of inputs')
+                             'on a list of of at least 2 inputs')
         if all([shape is None for shape in input_shape]):
             return
         reduced_inputs_shapes = [list(shape) for shape in input_shape]