diff --git a/pkgs/sagemath-standard/setup.py b/pkgs/sagemath-standard/setup.py
index dec74abd491..29c8744f910 100755
--- a/pkgs/sagemath-standard/setup.py
+++ b/pkgs/sagemath-standard/setup.py
@@ -64,7 +64,7 @@
 #########################################################
 
 if any(x in sys.argv
-       for x in ['build', 'bdist_wheel', 'install']):
+       for x in ['build', 'build_ext', 'bdist_wheel', 'install']):
     log.info("Generating auto-generated sources")
     from sage_setup.autogen import autogen_all
     autogen_all()