diff --git a/tools/finalization/environment.sh b/tools/finalization/environment.sh
index 7961e8b..cadc26f 100755
--- a/tools/finalization/environment.sh
+++ b/tools/finalization/environment.sh
@@ -15,7 +15,7 @@
 # We might or might not fix this in future, but for now let's keep it +1.
 export FINAL_PLATFORM_SDK_VERSION='35'
 # Feel free to randomize once in a while to detect buggy version detection code.
-export FINAL_MAINLINE_EXTENSION='58'
+export FINAL_MAINLINE_EXTENSION='13'
 
 # Options:
 # 'unfinalized' - branch is in development state,