diff --git a/mercurial/configitems.py b/mercurial/configitems.py
--- a/mercurial/configitems.py
+++ b/mercurial/configitems.py
@@ -22,7 +22,7 @@ def loadconfigtable(ui, extname, configt
         knownkeys = set(knownitems)
         newkeys = set(items)
         for key in sorted(knownkeys & newkeys):
-            msg = b"extension '%s' overwrite config item '%s.%s'"
+            msg = b"extension '%s' overwrites config item '%s.%s'"
             msg %= (extname, section, key)
             ui.develwarn(msg, config=b'warn-config')
 
diff --git a/tests/test-devel-warnings.t b/tests/test-devel-warnings.t
--- a/tests/test-devel-warnings.t
+++ b/tests/test-devel-warnings.t
@@ -455,10 +455,10 @@ Test warning on config option access and
   > EOF
 
   $ hg --config "extensions.buggyconfig=${TESTTMP}/buggyconfig.py" buggyconfig
-  devel-warn: extension 'buggyconfig' overwrite config item 'ui.interactive' at: */mercurial/extensions.py:* (_loadextra) (glob) (no-pyoxidizer !)
-  devel-warn: extension 'buggyconfig' overwrite config item 'ui.quiet' at: */mercurial/extensions.py:* (_loadextra) (glob) (no-pyoxidizer !)
-  devel-warn: extension 'buggyconfig' overwrite config item 'ui.interactive' at: mercurial.extensions:* (_loadextra) (glob) (pyoxidizer !)
-  devel-warn: extension 'buggyconfig' overwrite config item 'ui.quiet' at: mercurial.extensions:* (_loadextra) (glob) (pyoxidizer !)
+  devel-warn: extension 'buggyconfig' overwrites config item 'ui.interactive' at: */mercurial/extensions.py:* (_loadextra) (glob) (no-pyoxidizer !)
+  devel-warn: extension 'buggyconfig' overwrites config item 'ui.quiet' at: */mercurial/extensions.py:* (_loadextra) (glob) (no-pyoxidizer !)
+  devel-warn: extension 'buggyconfig' overwrites config item 'ui.interactive' at: mercurial.extensions:* (_loadextra) (glob) (pyoxidizer !)
+  devel-warn: extension 'buggyconfig' overwrites config item 'ui.quiet' at: mercurial.extensions:* (_loadextra) (glob) (pyoxidizer !)
   devel-warn: specifying a mismatched default value for a registered config item: 'ui.quiet' 'True' at: $TESTTMP/buggyconfig.py:* (cmdbuggyconfig) (glob)
   devel-warn: specifying a mismatched default value for a registered config item: 'ui.interactive' 'False' at: $TESTTMP/buggyconfig.py:* (cmdbuggyconfig) (glob)
   devel-warn: specifying a mismatched default value for a registered config item: 'test.some' 'bar' at: $TESTTMP/buggyconfig.py:* (cmdbuggyconfig) (glob)