diff --git a/setupbase.py b/setupbase.py
index 87b2a0b..a7eb5d9 100644
--- a/setupbase.py
+++ b/setupbase.py
@@ -116,6 +116,7 @@ def find_packages():
     add_package(packages, 'external.Itpl')
     add_package(packages, 'external.mglob')
     add_package(packages, 'external.path')
+    add_package(packages, 'external.pexpect')
     add_package(packages, 'external.pyparsing')
     add_package(packages, 'external.simplegeneric')
     add_package(packages, 'external.validate')