diff --git a/toolkit/mozapps/extensions/AddonManager.jsm b/toolkit/mozapps/extensions/AddonManager.jsm
index 29cf747494..d453a8981b 100644
--- a/toolkit/mozapps/extensions/AddonManager.jsm
+++ b/toolkit/mozapps/extensions/AddonManager.jsm
@@ -47,7 +47,7 @@ const KEY_APPDIR                      = "XCurProcD";
 const FILE_BLOCKLIST                  = "blocklist.xml";
 
 const BRANCH_REGEXP                   = /^([^\.]+\.[0-9]+[a-z]*).*/gi;
-const PREF_EM_CHECK_COMPATIBILITY = "extensions.checkCompatibility";
+const PREF_EM_CHECK_COMPATIBILITY = "extensions.enableCompatibilityChecking";
 
 const TOOLKIT_ID                      = "toolkit@mozilla.org";
 
diff --git a/toolkit/mozapps/webextensions/AddonManager.jsm b/toolkit/mozapps/webextensions/AddonManager.jsm
index 9aa2b8e7b7..a3bcbb504e 100644
--- a/toolkit/mozapps/webextensions/AddonManager.jsm
+++ b/toolkit/mozapps/webextensions/AddonManager.jsm
@@ -58,7 +58,7 @@ const KEY_APPDIR                      = "XCurProcD";
 const FILE_BLOCKLIST                  = "blocklist.xml";
 
 const BRANCH_REGEXP                   = /^([^\.]+\.[0-9]+[a-z]*).*/gi;
-const PREF_EM_CHECK_COMPATIBILITY = "extensions.checkCompatibility";
+const PREF_EM_CHECK_COMPATIBILITY = "extensions.enableCompatibilityChecking";
 
 const TOOLKIT_ID                      = "toolkit@mozilla.org";