diff --git a/browser/app/profile/firefox.js b/browser/app/profile/firefox.js
index cd4598700e00..8e5b672abbc8 100644
--- a/browser/app/profile/firefox.js
+++ b/browser/app/profile/firefox.js
@@ -129,8 +129,9 @@ pref("app.update.cert.maxErrors", 5);
 // the |app.update.url.override| preference should ONLY be used for testing.
 // IMPORTANT! metro.js should also be updated for updates to certs.X.issuerName
 
-// Nightly builds have switched over to aus4.mozilla.org, but we don't want anything else to yet.
-#ifdef NIGHTLY_BUILD
+// Non-release builds (Nightly, Aurora, etc.) have been switched over to aus4.mozilla.org.
+// This condition protects us against accidentally using it for release builds.
+#ifndef RELEASE_BUILD
 pref("app.update.certs.1.issuerName", "CN=DigiCert Secure Server CA,O=DigiCert Inc,C=US");
 pref("app.update.certs.1.commonName", "aus4.mozilla.org");
 
@@ -172,7 +173,7 @@ pref("app.update.silent", false);
 pref("app.update.staging.enabled", true);
 
 // Update service URL:
-#ifdef NIGHTLY_BUILD
+#ifndef RELEASE_BUILD
 pref("app.update.url", "https://aus4.mozilla.org/update/3/%PRODUCT%/%VERSION%/%BUILD_ID%/%BUILD_TARGET%/%LOCALE%/%CHANNEL%/%OS_VERSION%/%DISTRIBUTION%/%DISTRIBUTION_VERSION%/update.xml");
 #else
 pref("app.update.url", "https://aus3.mozilla.org/update/3/%PRODUCT%/%VERSION%/%BUILD_ID%/%BUILD_TARGET%/%LOCALE%/%CHANNEL%/%OS_VERSION%/%DISTRIBUTION%/%DISTRIBUTION_VERSION%/update.xml");
diff --git a/browser/metro/profile/metro.js b/browser/metro/profile/metro.js
index a950f2983478..7b6bb17e02e3 100644
--- a/browser/metro/profile/metro.js
+++ b/browser/metro/profile/metro.js
@@ -449,7 +449,7 @@ pref("app.update.silent", true);
 pref("app.update.staging.enabled", true);
 
 // Update service URL:
-#ifdef NIGHTLY_BUILD
+#ifndef RELEASE_BUILD
 pref("app.update.url", "https://aus4.mozilla.org/update/3/%PRODUCT%/%VERSION%/%BUILD_ID%/%BUILD_TARGET%/%LOCALE%/%CHANNEL%/%OS_VERSION%/%DISTRIBUTION%/%DISTRIBUTION_VERSION%/update.xml");
 #else
 pref("app.update.url", "https://aus3.mozilla.org/update/3/%PRODUCT%/%VERSION%/%BUILD_ID%/%BUILD_TARGET%/%LOCALE%/%CHANNEL%/%OS_VERSION%/%DISTRIBUTION%/%DISTRIBUTION_VERSION%/update.xml");
@@ -522,8 +522,9 @@ pref("app.update.cert.maxErrors", 5);
 // the |app.update.url.override| preference should ONLY be used for testing.
 // IMPORTANT! firefox.js should also be updated for updates to certs.X.issuerName
 
-// Nightly builds have switched over to aus4.mozilla.org, but we don't want anything else to yet.
-#ifdef NIGHTLY_BUILD
+// Non-release builds (Nightly, Aurora, etc.) have been switched over to aus4.mozilla.org.
+// This condition protects us against accidentally using it for release builds.
+#ifndef RELEASE_BUILD
 pref("app.update.certs.1.issuerName", "CN=DigiCert Secure Server CA,O=DigiCert Inc,C=US");
 pref("app.update.certs.1.commonName", "aus4.mozilla.org");
 pref("app.update.certs.2.issuerName", "CN=Thawte SSL CA,O=\"Thawte, Inc.\",C=US");