diff --git a/project_generator/exporters/uvision_definitions.py b/project_generator/exporters/uvision_definitions.py
index <HASH>..<HASH> 100644
--- a/project_generator/exporters/uvision_definitions.py
+++ b/project_generator/exporters/uvision_definitions.py
@@ -20,9 +20,8 @@ class uVisionDefinitions():
         try:
             return self.mcu_def[name]
         except KeyError:
-            pass
-            # raise RuntimeError(
-            #     "Mcu was not recognized for uvision. Please check mcu_def dictionary.")
+            raise RuntimeError(
+                "Mcu was not recognized for uvision. Please check mcu_def dictionary.")
 
     # MCU definitions which are currently supported. Add a new one, define a name as it is
     # in uVision, create an empty project for that MCU, open the project file (uvproj) in any text
uvision def - error uncommented, mcu has to be defined, via board or mcu