diff --git a/tests/Makefile b/tests/Makefile
index 57509ee..67c4f59 100644
--- a/tests/Makefile
+++ b/tests/Makefile
@@ -55,7 +55,7 @@ ussd: $(ussd_OBJS)
 tests.log: hayes modems pdu plugins tests.sh ussd
 	./tests.sh -P "$(PREFIX)" -- "tests.log"
 
-hayes.o: hayes.c ../src/modems/hayes.o
+hayes.o: hayes.c ../src/modems/hayes.o ../config.h
 	$(CC) $(hayes_CFLAGS) -c hayes.c
 
 modems.o: modems.c
diff --git a/tests/project.conf b/tests/project.conf
index d460a67..821bf0e 100644
--- a/tests/project.conf
+++ b/tests/project.conf
@@ -12,7 +12,7 @@ ldflags=`pkg-config --libs glib-2.0 libSystem`
 sources=hayes.c
 
 [hayes.c]
-depends=../src/modems/hayes.o
+depends=../src/modems/hayes.o,../config.h
 
 [modems]
 type=binary