diff --git a/lib/spack/spack/cmd/list.py b/lib/spack/spack/cmd/list.py
index 99bc64e991f..5c7051d6a90 100644
--- a/lib/spack/spack/cmd/list.py
+++ b/lib/spack/spack/cmd/list.py
@@ -23,8 +23,8 @@
 # Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 ##############################################################################
 import sys
-import argparse
 import llnl.util.tty as tty
+from external import argparse
 from llnl.util.tty.colify import colify
 
 import spack