--- a/Makefile.in
+++ b/Makefile.in
@@ -30,17 +30,23 @@ DIST_GARBAGE = config.cache config.log c
    netwerk/necko-config.h xpcom/xpcom-config.h xpcom/xpcom-private.h \
    .mozconfig.mk
 
 ifndef MOZ_PROFILE_USE
 # Automation builds should always have a new buildid, but for the sake of not
 # re-linking libxul on every incremental build we do not enforce this for
 # developer builds.  Tests always need a new buildid as well.
 ifneq (,$(MOZ_AUTOMATION)$(MOZ_BUILD_DATE)$(TEST_MOZBUILD))
-buildid.h source-repo.h: FORCE
+$(MDDEPDIR)/buildid.h.stub $(MDDEPDIR)/source-repo.h.stub: FORCE
+endif
+# Additionally, provide a dummy target during tests, because
+# faster/rules.mk will expect these targets to exist.
+ifdef TEST_MOZBUILD
+source-repo.h: $(MDDEPDIR)/source-repo.h.stub
+buildid.h: $(MDDEPDIR)/buildid.h.stub
 endif
 endif
 
 ifdef JS_STANDALONE
 configure_dir = $(topsrcdir)/js/src
 else
 configure_dir = $(topsrcdir)
 endif