diff --git a/Makefile b/Makefile
index 5cfd73d..dc73ba3 100644
--- a/Makefile
+++ b/Makefile
@@ -1,10 +1,11 @@
 FOLDER:=.
+ERROR:=255
 
 exec:
-	find $(FOLDER) -iname '*.ipynb' -print0 | xargs -n 1 -0 sh -c 'jupyter nbconvert --execute --ClearOutputPreprocessor.enabled=True --inplace $$0 || exit 255'
+	find $(FOLDER) -iname '*.ipynb' -print0 | xargs -n 1 -0 sh -c 'jupyter nbconvert --execute --ClearOutputPreprocessor.enabled=True --inplace $$0 || exit $(ERROR)'
 
 clean:
-	find $(FOLDER) -iname '*.ipynb' -print0 | xargs -n 1 -0 sh -c 'jupyter nbconvert --ClearOutputPreprocessor.enabled=True --inplace $$0 || exit 255'
+	find $(FOLDER) -iname '*.ipynb' -print0 | xargs -n 1 -0 sh -c 'nbstripout $$0 || exit $(ERROR)'
 
 
 .PHONY: exec clean