diff --git a/setup.py b/setup.py
index 9f60e71ad84..589e5685e66 100644
--- a/setup.py
+++ b/setup.py
@@ -429,6 +429,9 @@ class PyBuildExt(build_ext):
                 libs = []
             exts.append( Extension('crypt', ['cryptmodule.c'], libraries=libs) )
 
+        # CSV files
+        exts.append( Extension('_csv', ['_csv.c']) )
+
         # socket(2)
         exts.append( Extension('_socket', ['socketmodule.c'],
                                depends = ['socketmodule.h']) )