-batteryviewer: batteryviewer.c
- gcc $(shell pkg-config --cflags gtk4) -o $@ $< $(shell pkg-config --libs gtk4)
+batteryviewer: batteryviewer.c chart.c
+ gcc $(shell pkg-config --cflags gtk+-3.0) -o $@ $(CFLAGS) $^ $(shell pkg-config --libs gtk+-3.0)