diff --git a/makefile b/makefile
index 9621a2d..3237520 100644
--- a/makefile
+++ b/makefile
@@ -19,6 +19,9 @@ test_gui: test_gui.o gui.o engine.o lib/microui.o
 test_cli: test_cli.o engine.o cli.o
 	$(CC) $(CFLAGS) -o $@ $^ $(LDFLAGS)
 
+test_double_process: test_double_process.o engine.o
+	$(CC) $(CFLAGS) -o $@ $^ $(LDFLAGS)
+
 main.o: main.c engine.h tui.h
 	$(CC) $(CFLAGS) -c -o $@ $<
 
@@ -46,6 +49,9 @@ test_gui.o: test_gui.c gui.h engine.h
 test_cli.o: test_cli.c engine.h
 	$(CC) $(CFLAGS) -c -o $@ $<
 
+test_double_process.o: test_double_process.c engine.h
+	$(CC) $(CFLAGS) -c -o $@ $<
+
 cli.o: cli.c cli.h engine.h
 	$(CC) $(CFLAGS) -c -o $@ $<
 
@@ -54,7 +60,8 @@ cli.o: cli.c cli.h engine.h
 clean:
 	rm -f *.o lib/microui.o jack-looper test_engine test_tui test_gui test_cli
 
-test: test_engine test_tui test_cli
+test: test_engine test_tui test_cli test_double_process
 	./test_engine
 	./test_tui
 	./test_cli
+	./test_double_process