diff --git a/chapter.mk b/chapter.mk
index d6ae1cf..7d8f918 100644
--- a/chapter.mk
+++ b/chapter.mk
@@ -9,8 +9,8 @@ pythonplots : $(PYPDFFILES)
 
 $(PYPDFFILES) : %.pdf: %.py
 	echo $$(which python)
-	#python3 $<
-	python $<
+	python3 $<
+	#python $<
 
 cleanpythonplots :
 	rm -f $(PYPDFFILES)