diff --git a/toolkit/mozapps/extensions/test/browser/browser_globalwarnings.js b/toolkit/mozapps/extensions/test/browser/browser_globalwarnings.js
index 0541f0c9afef..663905a90fd0 100644
--- a/toolkit/mozapps/extensions/test/browser/browser_globalwarnings.js
+++ b/toolkit/mozapps/extensions/test/browser/browser_globalwarnings.js
@@ -16,23 +16,8 @@ function end_test() {
 add_test(function() {
   info("Testing compatibility checking warning");
 
-  var channel = "default";
-  try {
-    channel = Services.prefs.getCharPref("app.update.channel");
-  }
-  catch (e) { }
-  if (channel != "aurora" &&
-      channel != "beta" &&
-      channel != "release") {
-    var version = "nightly";
-  }
-  else {
-    version = Services.appinfo.version.replace(/^([^\.]+\.[0-9]+[a-z]*).*/gi, "$1");
-  }
-
-  var pref = "extensions.checkCompatibility." + version;
-  info("Setting " + pref + " pref to false")
-  Services.prefs.setBoolPref(pref, false);
+  info("Setting checkCompatibility to false");
+  AddonManager.checkCompatibility = false;
 
   open_manager("addons://list/extension", function(aWindow) {
     var hbox = aWindow.document.querySelector("#list-view hbox.global-warning-checkcompatibility");
@@ -42,7 +27,7 @@ add_test(function() {
 
     info("Clicking 'Enable' button");
     EventUtils.synthesizeMouse(button, 2, 2, { }, aWindow);
-    is(Services.prefs.prefHasUserValue(pref), false, "Check Compatibility pref should be cleared");
+    is(AddonManager.checkCompatibility, true, "Check Compatibility pref should be cleared");
     is_element_hidden(hbox, "Check Compatibility warning hbox should be hidden");
     is_element_hidden(button, "Check Compatibility warning button should be hidden");
 
diff --git a/toolkit/mozapps/extensions/test/browser/browser_searching.js b/toolkit/mozapps/extensions/test/browser/browser_searching.js
index 6bfcac66f418..d08fe89f3be8 100644
--- a/toolkit/mozapps/extensions/test/browser/browser_searching.js
+++ b/toolkit/mozapps/extensions/test/browser/browser_searching.js
@@ -19,22 +19,6 @@ var gProvider;
 var gServer;
 var gAddonInstalled = false;
 
-var channel = "default";
-try {
-  channel = Services.prefs.getCharPref("app.update.channel");
-}
-catch (e) { }
-if (channel != "aurora" &&
-    channel != "beta" &&
-    channel != "release") {
-  var version = "nightly";
-}
-else {
-  version = Services.appinfo.version.replace(/^([^\.]+\.[0-9]+[a-z]*).*/gi, "$1");
-}
-
-const COMPATIBILITY_PREF = "extensions.checkCompatibility." + version;
-
 function test() {
   requestLongerTimeout(2);
   // Turn on searching for this test
@@ -603,16 +587,16 @@ add_test(function() {
 
 // Tests that incompatible add-ons are shown with a warning if compatibility checking is disabled
 add_test(function() {
-  Services.prefs.setBoolPref(COMPATIBILITY_PREF, false);
+  AddonManager.checkCompatibility = false;
   search("incompatible", false, function() {
     var item = get_addon_item("remote5");
     is_element_visible(item, "Incompatible addon should be visible");
     is(item.getAttribute("notification"), "warning", "Compatibility warning should be shown");
 
-    var item = get_addon_item("remote6");
+    item = get_addon_item("remote6");
     is(item, null, "Addon incompatible with the product should not be visible");
 
-    Services.prefs.clearUserPref(COMPATIBILITY_PREF);
+    AddonManager.checkCompatibility = true;
     run_next_test();
   });
 });
diff --git a/toolkit/mozapps/extensions/test/xpcshell/head_addons.js b/toolkit/mozapps/extensions/test/xpcshell/head_addons.js
index 95e77599627d..7ed0bedbaf5e 100644
--- a/toolkit/mozapps/extensions/test/xpcshell/head_addons.js
+++ b/toolkit/mozapps/extensions/test/xpcshell/head_addons.js
@@ -26,6 +26,16 @@ var gAddonsList;
 
 var TEST_UNPACKED = false;
 
+function isNightlyChannel() {
+  var channel = "default";
+  try {
+    channel = Services.prefs.getCharPref("app.update.channel");
+  }
+  catch (e) { }
+
+  return channel != "aurora" && channel != "beta" && channel != "release" && channel != "esr";
+}
+
 function createAppInfo(id, name, version, platformVersion) {
   gAppInfo = {
     // nsIXULAppInfo
diff --git a/toolkit/mozapps/extensions/test/xpcshell/test_AddonRepository_compatmode.js b/toolkit/mozapps/extensions/test/xpcshell/test_AddonRepository_compatmode.js
index 78d7e4ac6bb2..aaf368ba4f37 100644
--- a/toolkit/mozapps/extensions/test/xpcshell/test_AddonRepository_compatmode.js
+++ b/toolkit/mozapps/extensions/test/xpcshell/test_AddonRepository_compatmode.js
@@ -15,19 +15,6 @@ function run_test() {
   do_test_pending();
   createAppInfo("xpcshell@tests.mozilla.org", "XPCShell", "1", "1.9.2");
 
-  var channel = "default";
-  try {
-    channel = Services.prefs.getCharPref("app.update.channel");
-  } catch (e) { }
-  if (channel != "aurora" &&
-      channel != "beta" &&
-      channel != "release") {
-    var version = "nightly";
-  } else {
-    version = Services.appinfo.version.replace(/^([^\.]+\.[0-9]+[a-z]*).*/gi, "$1");
-  }
-  COMPATIBILITY_PREF = "extensions.checkCompatibility." + version;
-
   // Create and configure the HTTP server.
   gServer = new HttpServer();
   gServer.registerDirectory("/data/", do_get_file("data"));
@@ -84,7 +71,7 @@ function run_test_2() {
 // Compatibility checking disabled.
 function run_test_3() {
   do_print("Testing with all compatibility checking disabled");
-  Services.prefs.setBoolPref(COMPATIBILITY_PREF, false);
+  AddonManager.checkCompatibility = false;
 
   AddonRepository.searchAddons("test", 6, {
     searchSucceeded: function(aAddons) {
diff --git a/toolkit/mozapps/extensions/test/xpcshell/test_bug470377_2.js b/toolkit/mozapps/extensions/test/xpcshell/test_bug470377_2.js
index 59c6baf50e9a..3deff9ffb30a 100644
--- a/toolkit/mozapps/extensions/test/xpcshell/test_bug470377_2.js
+++ b/toolkit/mozapps/extensions/test/xpcshell/test_bug470377_2.js
@@ -5,21 +5,8 @@
 
 // Disables security checking our updates which haven't been signed
 Services.prefs.setBoolPref("extensions.checkUpdateSecurity", false);
-// Disables compatibility checking
-var channel = "default";
-try {
-  channel = Services.prefs.getCharPref("app.update.channel");
-}
-catch (e) { }
 
-if (channel != "aurora" &&
-    channel != "beta" &&
-    channel != "release") {
-  Services.prefs.setBoolPref("extensions.checkCompatibility.nightly", false);
-}
-else {
-  Services.prefs.setBoolPref("extensions.checkCompatibility.2", false);
-}
+AddonManager.checkCompatibility = false;
 
 var ADDONS = [
   "test_bug470377_1",
diff --git a/toolkit/mozapps/extensions/test/xpcshell/test_bug470377_3.js b/toolkit/mozapps/extensions/test/xpcshell/test_bug470377_3.js
index 7c398c44d6d8..f20fdc5e2c4b 100644
--- a/toolkit/mozapps/extensions/test/xpcshell/test_bug470377_3.js
+++ b/toolkit/mozapps/extensions/test/xpcshell/test_bug470377_3.js
@@ -69,21 +69,8 @@ function run_test_1() {
 }
 
 function run_test_2() {
-  // Disable compatibility checks
-  var channel = "default";
-  try {
-    channel = Services.prefs.getCharPref("app.update.channel");
-  }
-  catch (e) { }
+  AddonManager.checkCompatibility = false;
 
-  if (channel != "aurora" &&
-      channel != "beta" &&
-      channel != "release") {
-    Services.prefs.setBoolPref("extensions.checkCompatibility.nightly", false);
-  }
-  else {
-    Services.prefs.setBoolPref("extensions.checkCompatibility.2.2", false);
-  }
   restartManager();
 
   AddonManager.getAddonsByIDs(["bug470377_1@tests.mozilla.org",
diff --git a/toolkit/mozapps/extensions/test/xpcshell/test_bug470377_3_strictcompat.js b/toolkit/mozapps/extensions/test/xpcshell/test_bug470377_3_strictcompat.js
index c7acfeb3b6ba..d293ae87de1a 100644
--- a/toolkit/mozapps/extensions/test/xpcshell/test_bug470377_3_strictcompat.js
+++ b/toolkit/mozapps/extensions/test/xpcshell/test_bug470377_3_strictcompat.js
@@ -68,21 +68,8 @@ function run_test_1() {
 }
 
 function run_test_2() {
-  // Disable compatibility checks
-  var channel = "default";
-  try {
-    channel = Services.prefs.getCharPref("app.update.channel");
-  }
-  catch (e) { }
+  AddonManager.checkCompatibility = false;
 
-  if (channel != "aurora" &&
-      channel != "beta" &&
-      channel != "release") {
-    Services.prefs.setBoolPref("extensions.checkCompatibility.nightly", false);
-  }
-  else {
-    Services.prefs.setBoolPref("extensions.checkCompatibility.2.2", false);
-  }
   restartManager();
 
   AddonManager.getAddonsByIDs(["bug470377_1@tests.mozilla.org",
diff --git a/toolkit/mozapps/extensions/test/xpcshell/test_bug470377_4.js b/toolkit/mozapps/extensions/test/xpcshell/test_bug470377_4.js
index 2a4d66494a63..378043597e1b 100644
--- a/toolkit/mozapps/extensions/test/xpcshell/test_bug470377_4.js
+++ b/toolkit/mozapps/extensions/test/xpcshell/test_bug470377_4.js
@@ -3,21 +3,6 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/.
  */
 
-var channel = "default";
-try {
-  channel = Services.prefs.getCharPref("app.update.channel");
-}
-catch (e) { }
-
-if (channel != "aurora" &&
-    channel != "beta" &&
-    channel != "release") {
-  var checkCompatPref = "extensions.checkCompatibility.nightly";
-}
-else {
-  checkCompatPref = "extensions.checkCompatibility.2.1a";
-}
-
 function run_test() {
   do_test_pending();
   createAppInfo("xpcshell@tests.mozilla.org", "XPCShell", "2.1a4", "2");
@@ -55,8 +40,8 @@ function run_test() {
 }
 
 function run_test_1() {
-  // Disable compatibility checks
-  Services.prefs.setBoolPref(checkCompatPref, false);
+  AddonManager.checkCompatibility = false;
+
   startupManager();
 
   AddonManager.getAddonsByIDs(["bug470377_1@tests.mozilla.org",
@@ -81,8 +66,8 @@ function run_test_1() {
 }
 
 function run_test_2() {
-  // Enable compatibility checks
-  Services.prefs.setBoolPref(checkCompatPref, true);
+  AddonManager.checkCompatibility = true;
+
   restartManager();
 
   AddonManager.getAddonsByIDs(["bug470377_1@tests.mozilla.org",
diff --git a/toolkit/mozapps/extensions/test/xpcshell/test_bug521905.js b/toolkit/mozapps/extensions/test/xpcshell/test_bug521905.js
index 1c474947aa66..d978acce5cee 100644
--- a/toolkit/mozapps/extensions/test/xpcshell/test_bug521905.js
+++ b/toolkit/mozapps/extensions/test/xpcshell/test_bug521905.js
@@ -8,21 +8,12 @@ const ID = "bug521905@tests.mozilla.org";
 
 // Disables security checking our updates which haven't been signed
 Services.prefs.setBoolPref("extensions.checkUpdateSecurity", false);
-// Disables compatibility checking
-Services.prefs.setBoolPref("extensions.checkCompatibility.2.0pre", false);
+AddonManager.checkCompatibility = false;
 
 function run_test() {
-  var channel = "default";
-  try {
-    channel = Services.prefs.getCharPref("app.update.channel");
-  }
-  catch (e) { }
-
   // This test is only relevant on builds where the version is included in the
   // checkCompatibility preference name
-  if (channel != "aurora" &&
-      channel != "beta" &&
-      channel != "release") {
+  if (isNightlyChannel()) {
     return;
   }
 
diff --git a/toolkit/mozapps/extensions/test/xpcshell/test_checkcompatibility.js b/toolkit/mozapps/extensions/test/xpcshell/test_checkcompatibility.js
index a49cafc7bd26..b87e3518de05 100644
--- a/toolkit/mozapps/extensions/test/xpcshell/test_checkcompatibility.js
+++ b/toolkit/mozapps/extensions/test/xpcshell/test_checkcompatibility.js
@@ -69,15 +69,7 @@ function run_test() {
     writeInstallRDFForExtension(a, profileDir);
   });
 
-  var channel = "default";
-  try {
-    channel = Services.prefs.getCharPref("app.update.channel");
-  }
-  catch (e) { }
-
-  gIsNightly = channel != "aurora" &&
-               channel != "beta" &&
-               channel != "release";
+  gIsNightly = isNightlyChannel();
 
   startupManager();
 
diff --git a/toolkit/mozapps/extensions/test/xpcshell/test_pref_properties.js b/toolkit/mozapps/extensions/test/xpcshell/test_pref_properties.js
index e7961a9fac07..c6a10e7c1772 100644
--- a/toolkit/mozapps/extensions/test/xpcshell/test_pref_properties.js
+++ b/toolkit/mozapps/extensions/test/xpcshell/test_pref_properties.js
@@ -128,13 +128,7 @@ function run_test() {
 
 
   // AddonManager.checkCompatibility
-  var channel = "default";
-  try {
-    channel = Services.prefs.getCharPref("app.update.channel");
-  } catch (e) { }
-  if (channel != "aurora" &&
-      channel != "beta" &&
-      channel != "release") {
+  if (isNightlyChannel()) {
     var version = "nightly";
   } else {
     version = Services.appinfo.version.replace(/^([^\.]+\.[0-9]+[a-z]*).*/gi, "$1");
diff --git a/toolkit/mozapps/extensions/test/xpcshell/test_update_compatmode.js b/toolkit/mozapps/extensions/test/xpcshell/test_update_compatmode.js
index 8842fdc109c4..6128f43cd1d3 100644
--- a/toolkit/mozapps/extensions/test/xpcshell/test_update_compatmode.js
+++ b/toolkit/mozapps/extensions/test/xpcshell/test_update_compatmode.js
@@ -14,25 +14,10 @@ var testserver;
 const profileDir = gProfD.clone();
 profileDir.append("extensions");
 
-var COMPATIBILITY_PREF;
-
 function run_test() {
   do_test_pending();
   createAppInfo("xpcshell@tests.mozilla.org", "XPCShell", "1", "1.9.2");
   
-  var channel = "default";
-  try {
-    channel = Services.prefs.getCharPref("app.update.channel");
-  } catch (e) { }
-  if (channel != "aurora" &&
-      channel != "beta" &&
-      channel != "release") {
-    var version = "nightly";
-  } else {
-    version = Services.appinfo.version.replace(/^([^\.]+\.[0-9]+[a-z]*).*/gi, "$1");
-  }
-  COMPATIBILITY_PREF = "extensions.checkCompatibility." + version;
-
   // Create and configure the HTTP server.
   testserver = new HttpServer();
   testserver.registerDirectory("/data/", do_get_file("data"));
@@ -174,7 +159,7 @@ function run_test_3() {
 // Compatibility checking disabled.
 function run_test_4() {
   do_print("Testing with all compatibility checking disabled");
-  Services.prefs.setBoolPref(COMPATIBILITY_PREF, false);
+  AddonManager.checkCompatibility = false;
   AddonManager.getAddonByID("compatmode-ignore@tests.mozilla.org", function(addon) {
     do_check_neq(addon, null);
     addon.findUpdates({
diff --git a/toolkit/mozapps/extensions/test/xpcshell/test_updatecheck.js b/toolkit/mozapps/extensions/test/xpcshell/test_updatecheck.js
index 0cea7c5251dc..8b7dc4cfbdfb 100644
--- a/toolkit/mozapps/extensions/test/xpcshell/test_updatecheck.js
+++ b/toolkit/mozapps/extensions/test/xpcshell/test_updatecheck.js
@@ -6,24 +6,12 @@
 
 Components.utils.import("resource://gre/modules/AddonUpdateChecker.jsm");
 
-var COMPATIBILITY_PREF;
-
 Components.utils.import("resource://testing-common/httpd.js");
 var testserver;
 
 function run_test() {
   createAppInfo("xpcshell@tests.mozilla.org", "XPCShell", "1", "1.9.2");
 
-  var channel = "default";
-  try {
-    channel = Services.prefs.getCharPref("app.update.channel");
-  } catch (e) { }
-  if (channel != "aurora" && channel != "beta" && channel != "release")
-    var version = "nightly";
-  else
-    version = Services.appinfo.version.replace(/^([^\.]+\.[0-9]+[a-z]*).*/gi, "$1");
-  COMPATIBILITY_PREF = "extensions.checkCompatibility." + version;
-
   // Create and configure the HTTP server.
   testserver = new HttpServer();
   testserver.registerDirectory("/data/", do_get_file("data"));