diff --git a/browser/app/profile/firefox.js b/browser/app/profile/firefox.js
index a8fddfeaae55..178e61b23b11 100644
--- a/browser/app/profile/firefox.js
+++ b/browser/app/profile/firefox.js
@@ -683,6 +683,10 @@ pref("plugin.defaultXpi.state", 2);
 pref("plugin.state.flash", 2);
 pref("plugin.state.java", 1);
 
+#ifdef NIGHTLY_BUILD
+pref("plugins.flashBlock.enabled", true);
+#endif
+
 #ifdef XP_WIN
 pref("browser.preferences.instantApply", false);
 #else