diff --git a/Tools/build/stable_abi.py b/Tools/build/stable_abi.py
index 88db93e935e9be..42b2dd92307bbf 100644
--- a/Tools/build/stable_abi.py
+++ b/Tools/build/stable_abi.py
@@ -684,7 +684,8 @@ def main():
 
     if args.all:
         run_all_generators = True
-        args.unixy_check = True
+        if UNIXY:
+            args.unixy_check = True
 
     try:
         file = args.file.open('rb')