diff --git a/mercurial/commands.py b/mercurial/commands.py
--- a/mercurial/commands.py
+++ b/mercurial/commands.py
@@ -1998,6 +1998,10 @@ def debuginstall(ui):
         ui.write(_(" (check that your locale is properly set)\n"))
         problems += 1
 
+    # Python lib
+    ui.status(_("checking Python lib (%s)...\n")
+              % os.path.dirname(os.__file__))
+
     # compiled modules
     ui.status(_("checking installed modules (%s)...\n")
               % os.path.dirname(__file__))
diff --git a/tests/test-install.t b/tests/test-install.t
--- a/tests/test-install.t
+++ b/tests/test-install.t
@@ -1,6 +1,7 @@
 hg debuginstall
   $ hg debuginstall
   checking encoding (ascii)...
+  checking Python lib (*lib*)... (glob)
   checking installed modules (*mercurial)... (glob)
   checking templates (*mercurial?templates)... (glob)
   checking commit editor...
@@ -10,6 +11,7 @@ hg debuginstall
 hg debuginstall with no username
   $ HGUSER= hg debuginstall
   checking encoding (ascii)...
+  checking Python lib (*lib*)... (glob)
   checking installed modules (*mercurial)... (glob)
   checking templates (*mercurial?templates)... (glob)
   checking commit editor...