diff --git a/c/makefile b/c/makefile
index d4f0dfe..b21d8cf 100644
--- a/c/makefile
+++ b/c/makefile
@@ -1,7 +1,15 @@
-OBJS = main.o hours.o
+DEPS = hours.o period.o
 
-wh: $(OBJS)
+wh: main.o $(DEPS)
 	gcc $^ -o $@
 
 %.o: %.c %.h
 	gcc -c $< -Wall
+
+.PHONY: test
+test: wh_tests
+	./wh_tests
+	rm ./wh_tests
+
+wh_tests: wh_tests.o $(DEPS)
+	gcc $^ -o $@