diff --git a/setup.py b/setup.py
index c1775b5..5051c6b 100755
--- a/setup.py
+++ b/setup.py
@@ -12,6 +12,10 @@
 
 ext_kwds = dict(include_dirs=include_dirs(), library_dirs=library_dirs())
 
+# Generate auto-generated sources from pari.desc
+# This needs to be done before build/build_ext so the generated pxd is moved
+# to the build directory and installed with newer setuptools.
+rebuild()
 
 if "READTHEDOCS" in os.environ:
     # When building with readthedocs, disable optimizations to decrease
@@ -28,9 +32,6 @@
 # Adapted from Cython's new_build_ext
 class build_ext(_build_ext):
     def finalize_options(self):
-        # Generate auto-generated sources from pari.desc
-        rebuild()
-
         self.directives = {
             "autotestdict.cdef": True,
             "binding": True,