--- a/browser/app/profile/firefox.js
+++ b/browser/app/profile/firefox.js
@@ -443,17 +443,21 @@ pref("browser.link.open_newwindow.restri
 // We set this differently on Mac because the fullscreen implementation there is
 // different.
 #ifdef XP_MACOSX
 pref("browser.link.open_newwindow.disabled_in_fullscreen", true);
 #else
 pref("browser.link.open_newwindow.disabled_in_fullscreen", false);
 #endif
 
+#ifdef NIGHTLY_BUILD
+pref("browser.photon.structure.enabled", true);
+#else
 pref("browser.photon.structure.enabled", false);
+#endif
 
 // Tabbed browser
 pref("browser.tabs.closeWindowWithLastTab", true);
 pref("browser.tabs.insertRelatedAfterCurrent", true);
 pref("browser.tabs.warnOnClose", true);
 pref("browser.tabs.warnOnCloseOtherTabs", true);
 pref("browser.tabs.warnOnOpen", true);
 pref("browser.tabs.maxOpenBeforeWarn", 15);