diff --git a/Makefile b/Makefile
index dc73ba3..f2f7dcb 100644
--- a/Makefile
+++ b/Makefile
@@ -1,5 +1,5 @@
 FOLDER:=.
-ERROR:=255
+ERROR:=255 
 
 exec:
 	find $(FOLDER) -iname '*.ipynb' -print0 | xargs -n 1 -0 sh -c 'jupyter nbconvert --execute --ClearOutputPreprocessor.enabled=True --inplace $$0 || exit $(ERROR)'