diff --git a/css/properties/background-size.json b/css/properties/background-size.json
index 49834fd1b4559d..1e5de907bbeea4 100644
--- a/css/properties/background-size.json
+++ b/css/properties/background-size.json
@@ -134,7 +134,7 @@
                 "version_added": "12"
               },
               "firefox": {
-                "version_added": "≤72"
+                "version_added": "3.6"
               },
               "firefox_android": "mirror",
               "ie": {