diff --git a/browser/components/downloads/Makefile.in b/browser/components/downloads/Makefile.in
index 6513edb70ba..6920622f05a 100644
--- a/browser/components/downloads/Makefile.in
+++ b/browser/components/downloads/Makefile.in
@@ -11,8 +11,6 @@ include $(DEPTH)/config/autoconf.mk
 
 DIRS = src
 
-ifdef ENABLE_TESTS
-DIRS += test
-endif
+TEST_DIRS += test
 
 include $(topsrcdir)/config/rules.mk
diff --git a/browser/components/thumbnails/Makefile.in b/browser/components/thumbnails/Makefile.in
index 5a7ccad7b56..4a51f7697f1 100644
--- a/browser/components/thumbnails/Makefile.in
+++ b/browser/components/thumbnails/Makefile.in
@@ -18,9 +18,7 @@ EXTRA_PP_JS_MODULES = \
 	PageThumbs.jsm \
 	$(NULL)
 
-ifdef ENABLE_TESTS
-	DIRS += test
-endif
+TEST_DIRS += test
 
 include $(topsrcdir)/config/rules.mk
 
diff --git a/browser/devtools/debugger/Makefile.in b/browser/devtools/debugger/Makefile.in
index 088d6e4b331..ed8461cf583 100644
--- a/browser/devtools/debugger/Makefile.in
+++ b/browser/devtools/debugger/Makefile.in
@@ -9,9 +9,7 @@ VPATH     = @srcdir@
 
 include $(DEPTH)/config/autoconf.mk
 
-ifdef ENABLE_TESTS
-	DIRS += test
-endif
+TEST_DIRS += test
 
 include $(topsrcdir)/config/rules.mk
 
diff --git a/browser/devtools/layoutview/Makefile.in b/browser/devtools/layoutview/Makefile.in
index cc895e850dd..d96152027a5 100644
--- a/browser/devtools/layoutview/Makefile.in
+++ b/browser/devtools/layoutview/Makefile.in
@@ -10,9 +10,7 @@ VPATH		= @srcdir@
 
 include $(DEPTH)/config/autoconf.mk
 
-ifdef ENABLE_TESTS
-	DIRS += test
-endif
+TEST_DIRS += test
 
 include $(topsrcdir)/config/rules.mk
 
diff --git a/content/media/Makefile.in b/content/media/Makefile.in
index 8a03fa0638a..e39a655a910 100644
--- a/content/media/Makefile.in
+++ b/content/media/Makefile.in
@@ -87,9 +87,7 @@ ifdef MOZ_MEDIA_PLUGINS
 PARALLEL_DIRS += plugins
 endif
 
-ifdef ENABLE_TESTS
-PARALLEL_DIRS += test
-endif
+TEST_DIRS += test
 
 FORCE_STATIC_LIB = 1
 
diff --git a/content/xul/content/Makefile.in b/content/xul/content/Makefile.in
index d088e925b45..ec5fe2a4d78 100644
--- a/content/xul/content/Makefile.in
+++ b/content/xul/content/Makefile.in
@@ -13,9 +13,7 @@ include $(DEPTH)/config/autoconf.mk
 MODULE		= xul
 PARALLEL_DIRS	= public src
 
-ifdef ENABLE_TESTS
-PARALLEL_DIRS	+= test
-endif
+TEST_DIRS	+= test
 
 include $(topsrcdir)/config/rules.mk
 
diff --git a/dom/contacts/Makefile.in b/dom/contacts/Makefile.in
index 4fcf5d25e5f..6ec7220927c 100644
--- a/dom/contacts/Makefile.in
+++ b/dom/contacts/Makefile.in
@@ -31,9 +31,7 @@ EXTRA_JS_MODULES =   \
   $(NULL)
 endif
 
-ifdef ENABLE_TESTS
-DIRS += tests
-endif
+TEST_DIRS += tests
 
 # Add VPATH to LOCAL_INCLUDES so we are going to include the correct backend
 # subdirectory (and the ipc one).
diff --git a/dom/power/Makefile.in b/dom/power/Makefile.in
index e7cfa56b7b6..9f855b3f826 100644
--- a/dom/power/Makefile.in
+++ b/dom/power/Makefile.in
@@ -36,9 +36,7 @@ XPIDLSRCS = \
   nsIPowerManagerService.idl \
   $(NULL)
 
-ifdef ENABLE_TESTS
-DIRS += test
-endif
+TEST_DIRS += test
 
 include $(topsrcdir)/config/config.mk
 include $(topsrcdir)/ipc/chromium/chromium-config.mk
diff --git a/dom/settings/Makefile.in b/dom/settings/Makefile.in
index 899c57b7e9e..929f50933a3 100644
--- a/dom/settings/Makefile.in
+++ b/dom/settings/Makefile.in
@@ -28,9 +28,7 @@ EXTRA_JS_MODULES =   \
   SettingsChangeNotifier.jsm \
   $(NULL)
 
-ifdef ENABLE_TESTS
-DIRS += tests
-endif
+TEST_DIRS += tests
 
 # Add VPATH to LOCAL_INCLUDES so we are going to include the correct backend
 # subdirectory (and the ipc one).
diff --git a/modules/libmar/Makefile.in b/modules/libmar/Makefile.in
index a40f500c4be..e14f1df9c0e 100644
--- a/modules/libmar/Makefile.in
+++ b/modules/libmar/Makefile.in
@@ -26,10 +26,8 @@ endif
 # If we are building ./sign and ./verify then ./tool must come after it
 DIRS += tool
 
-ifdef ENABLE_TESTS
 ifdef MOZ_ENABLE_SIGNMAR
-DIRS += tests
-endif
+TEST_DIRS += tests
 endif
 
 include $(topsrcdir)/config/rules.mk
diff --git a/toolkit/devtools/debugger/Makefile.in b/toolkit/devtools/debugger/Makefile.in
index b84d8a574e6..ab0f4a2f8d0 100644
--- a/toolkit/devtools/debugger/Makefile.in
+++ b/toolkit/devtools/debugger/Makefile.in
@@ -32,9 +32,7 @@ XPIDLSRCS = \
 	nsIJSInspector.idl \
 	$(NULL)
 
-ifdef ENABLE_TESTS
-    DIRS += tests
-endif
+TEST_DIRS += tests
 
 include $(topsrcdir)/config/rules.mk