diff --git a/setup.py b/setup.py
index 13db47077..d3297838d 100644
--- a/setup.py
+++ b/setup.py
@@ -61,7 +61,7 @@ def finalize_options(self):
         print("Finalizing options")
         _build_ext.finalize_options(self)
         # Prevent numpy from thinking it is still in its setup process:
-        set_builtin('__NUMPY_SETUP__', False)
+        set_builtin("__NUMPY_SETUP__", False)
         import numpy
 
         self.include_dirs.append(numpy.get_include())