diff --git a/Makefile b/Makefile
index 5d87ee0..091111c 100644
--- a/Makefile
+++ b/Makefile
@@ -9,8 +9,7 @@ all: $(EXERCISES)
 
 clean:
 	rm -f $(EXERCISES)
-	rm -f ex19
-	rm -f object.o
+	$(MAKE) -f ex19.mk clean
 
 
 .PHONY: all clean
diff --git a/ex19.mk b/ex19.mk
index aea800f..96e5d90 100644
--- a/ex19.mk
+++ b/ex19.mk
@@ -6,3 +6,4 @@ ex19: object.o
 
 clean:
 	rm -f ex19
+	rm -f object.o