diff --git a/webextensions/api/contentScriptGlobalScope.json b/webextensions/api/contentScriptGlobalScope.json
index 4f773f7a3e0da3..f280ff8ae3f835 100644
--- a/webextensions/api/contentScriptGlobalScope.json
+++ b/webextensions/api/contentScriptGlobalScope.json
@@ -10,7 +10,7 @@
             },
             "edge": "mirror",
             "firefox": {
-              "version_added": true
+              "version_added": "30"
             },
             "firefox_android": "mirror",
             "opera": "mirror",
@@ -29,7 +29,7 @@
               },
               "edge": "mirror",
               "firefox": {
-                "version_added": true
+                "version_added": "30"
               },
               "firefox_android": "mirror",
               "opera": "mirror",
@@ -49,7 +49,7 @@
               },
               "edge": "mirror",
               "firefox": {
-                "version_added": true
+                "version_added": "30"
               },
               "firefox_android": "mirror",
               "opera": "mirror",