diff --git a/Library/Homebrew/language/python.rb b/Library/Homebrew/language/python.rb
index a1bb1151e8..e231b047a8 100644
--- a/Library/Homebrew/language/python.rb
+++ b/Library/Homebrew/language/python.rb
@@ -308,7 +308,7 @@ module Language
             "--use-feature=no-binary-enable-wheel-cache",
             "--ignore-installed"
           ]
-          args << "--no-build-isolation" if not build_isolation
+          args << "--no-build-isolation" unless build_isolation
           @formula.system @venv_root/"bin/pip", "install", args, *targets
         end
       end