diff --git a/onnx2keras/converter.py b/onnx2keras/converter.py
index 616295cf..3b864ed9 100644
--- a/onnx2keras/converter.py
+++ b/onnx2keras/converter.py
@@ -137,6 +137,7 @@ def onnx_to_keras(onnx_model, input_names,
                 postfix = node_index if len(node.output) == 1 else "%s_%s" % (node_index, output_index)
                 keras_names.append('LAYER_%s' % postfix)
             else:
+                output = output.replace(":", "_")
                 keras_names.append(output)
 
         if len(node.output) != 1: