diff --git a/Makefile b/Makefile
index dd36202..3cc0991 100644
--- a/Makefile
+++ b/Makefile
@@ -7,4 +7,7 @@ day%/part2: day%
 	cd $< && $(MAKE)
 
 all: $(addsuffix /part2,$(DAYS))
+
+clean:
+	for d in "$(shell find . -type d -name day\*)"; do cd $$d && $(MAKE) clean; done
 		
diff --git a/day1/Makefile b/day1/Makefile
index 6a697e0..2d1d5cc 100644
--- a/day1/Makefile
+++ b/day1/Makefile
@@ -39,5 +39,5 @@ part2-big: input-big.h
 	strip $@
 
 clean:
-	rm -f part{1,2}
-	rm -f input.h
+	rm -f part{1,2}{,-big}
+	rm -f input{,-big}.h