diff --git a/browser/build.mk b/browser/build.mk
index 515a29db2432..da56b0fa5fc4 100644
--- a/browser/build.mk
+++ b/browser/build.mk
@@ -75,14 +75,8 @@ upload::
 ifdef ENABLE_TESTS
 # Implemented in testing/testsuite-targets.mk
 
-ifdef TEST_PATH
-BROWSER_TEST_PATH = --test-path=$(TEST_PATH)
-else
-BROWSER_TEST_PATH =
-endif
-
 mochitest-browser-chrome:
-	$(RUN_MOCHITEST) --browser-chrome $(BROWSER_TEST_PATH)
+	$(RUN_MOCHITEST) --browser-chrome
 	$(CHECK_TEST_ERROR)
 
 mochitest:: mochitest-browser-chrome
diff --git a/testing/testsuite-targets.mk b/testing/testsuite-targets.mk
index 39be116b8e8a..133e91f7bb04 100644
--- a/testing/testsuite-targets.mk
+++ b/testing/testsuite-targets.mk
@@ -35,9 +35,10 @@
 #
 # ***** END LICENSE BLOCK *****
 
+# Usage: |make [EXTRA_TEST_ARGS=...] mochitest*|.
 mochitest:: mochitest-plain mochitest-chrome mochitest-a11y
 
-RUN_MOCHITEST = rm -f ./$@.log && $(PYTHON) _tests/testing/mochitest/runtests.py --autorun --close-when-done --console-level=INFO  --log-file=./$@.log --file-level=INFO
+RUN_MOCHITEST = rm -f ./$@.log && $(PYTHON) _tests/testing/mochitest/runtests.py --autorun --close-when-done --console-level=INFO --log-file=./$@.log --file-level=INFO $(MOCHITEST_PATH) $(EXTRA_TEST_ARGS)
 
 ifndef NO_FAIL_ON_TEST_ERRORS
 define CHECK_TEST_ERROR
@@ -59,18 +60,19 @@ MOCHITEST_PATH =
 endif
 
 mochitest-plain:
-	$(RUN_MOCHITEST) $(MOCHITEST_PATH)
+	$(RUN_MOCHITEST)
 	$(CHECK_TEST_ERROR)
 
 mochitest-chrome:
-	$(RUN_MOCHITEST) --chrome $(MOCHITEST_PATH)
+	$(RUN_MOCHITEST) --chrome
 	$(CHECK_TEST_ERROR)
 
 mochitest-a11y:
-	$(RUN_MOCHITEST) --a11y $(MOCHITEST_PATH)
+	$(RUN_MOCHITEST) --a11y
 	$(CHECK_TEST_ERROR)
 
-RUN_REFTEST = rm -f ./$@.log && $(PYTHON) _tests/reftest/runreftest.py $(1) | tee ./$@.log
+# Usage: |make [EXTRA_TEST_ARGS=...] *test|.
+RUN_REFTEST = rm -f ./$@.log && $(PYTHON) _tests/reftest/runreftest.py $(EXTRA_TEST_ARGS) $(1) | tee ./$@.log
 
 reftest:
 	$(call RUN_REFTEST,$(topsrcdir)/layout/reftests/reftest.list)