diff --git a/testing/testsuite-targets.mk b/testing/testsuite-targets.mk
index 383fa05ead4..cdcb2adc467 100644
--- a/testing/testsuite-targets.mk
+++ b/testing/testsuite-targets.mk
@@ -95,16 +95,16 @@ mochitest-a11y:
 mochitest-ipcplugins:
 ifeq (Darwin,$(OS_ARCH))
 ifeq (i386,$(TARGET_CPU))
-	$(RUN_MOCHITEST) --setpref=dom.ipc.plugins.enabled.i386.test.plugin=true --test-path=modules/plugin/test
+	$(RUN_MOCHITEST) --setpref=dom.ipc.plugins.enabled.i386.test.plugin=false --test-path=modules/plugin/test
 endif
 ifeq (x86_64,$(TARGET_CPU))
-	$(RUN_MOCHITEST) --setpref=dom.ipc.plugins.enabled.x86_64.test.plugin=true --test-path=modules/plugin/test
+	$(RUN_MOCHITEST) --setpref=dom.ipc.plugins.enabled.x86_64.test.plugin=false --test-path=modules/plugin/test
 endif
 ifeq (powerpc,$(TARGET_CPU))
-	$(RUN_MOCHITEST) --setpref=dom.ipc.plugins.enabled.ppc.test.plugin=true --test-path=modules/plugin/test
+	$(RUN_MOCHITEST) --setpref=dom.ipc.plugins.enabled.ppc.test.plugin=false --test-path=modules/plugin/test
 endif
 else
-	$(RUN_MOCHITEST) --setpref=dom.ipc.plugins.enabled=true --test-path=modules/plugin/test
+	$(RUN_MOCHITEST) --setpref=dom.ipc.plugins.enabled=false --test-path=modules/plugin/test
 endif
 	$(CHECK_TEST_ERROR)