diff --git a/tools/gyp/pylib/gyp/mac_tool.py b/tools/gyp/pylib/gyp/mac_tool.py
index c61a3ef60bc735..ac19b6dc81fa6e 100755
--- a/tools/gyp/pylib/gyp/mac_tool.py
+++ b/tools/gyp/pylib/gyp/mac_tool.py
@@ -503,7 +503,8 @@ def _ExpandVariables(self, data, substitutions):
     if isinstance(data, list):
       return [self._ExpandVariables(v, substitutions) for v in data]
     if isinstance(data, dict):
-      return {k: self._ExpandVariables(data[k], substitutions) for k in data}
+      return dict((k, self._ExpandVariables(data[k],
+                                            substitutions)) for k in data)
     return data
 
 if __name__ == '__main__':