diff --git a/platform/firefox/frameModule.js b/platform/firefox/frameModule.js
index 285838a..e458c96 100644
--- a/platform/firefox/frameModule.js
+++ b/platform/firefox/frameModule.js
@@ -74,7 +74,7 @@ var contentObserver = {
     cpMessageName: hostName + ':shouldLoad',
     uniqueSandboxId: 1,
     modernFirefox: Services.appinfo.ID === '{ec8030f7-c20a-464f-9b0e-13a3a9e97384}' &&
-                   Services.vc.compare(Services.appinfo.platformVersion, '45.0') >= 0,
+                   Services.vc.compare(Services.appinfo.platformVersion, '44') > 0,
 
     get componentRegistrar() {
         return Components.manager.QueryInterface(Ci.nsIComponentRegistrar);
diff --git a/platform/firefox/vapi-background.js b/platform/firefox/vapi-background.js
index e826cf7..0475fc9 100644
--- a/platform/firefox/vapi-background.js
+++ b/platform/firefox/vapi-background.js
@@ -47,7 +47,7 @@ const {Services} = Cu.import('resource://gre/modules/Services.jsm', null);
 var vAPI = self.vAPI = self.vAPI || {};
 vAPI.firefox = true;
 vAPI.modernFirefox = Services.appinfo.ID === '{ec8030f7-c20a-464f-9b0e-13a3a9e97384}' &&
-                     Services.vc.compare(Services.appinfo.platformVersion, '45.0') >= 0;
+                     Services.vc.compare(Services.appinfo.platformVersion, '44') > 0;
 
 /******************************************************************************/