diff --git a/po/aurweb.pot b/po/aurweb.pot
index aeed9f02..1f7e8784 100644
--- a/po/aurweb.pot
+++ b/po/aurweb.pot
@@ -568,6 +568,15 @@ msgstr ""
 msgid "Flag Package Out-Of-Date"
 msgstr ""
 
+#: templates/packages/flag.html
+msgid "This seems to be a VCS package. Please do %snot%s flag "
+"it out-of-date if the package version in the AUR does "
+"not match the most recent commit. Flagging this package "
+"should only be done if the sources moved or changes in "
+"the PKGBUILD are required because of recent upstream "
+"changes."
+msgstr ""
+
 #: html/pkgflag.php
 #, php-format
 msgid ""
diff --git a/templates/packages/flag.html b/templates/packages/flag.html
index 4e133acb..0335cf18 100644
--- a/templates/packages/flag.html
+++ b/templates/packages/flag.html
@@ -18,6 +18,20 @@
             {% endfor %}
         </ul>
 
+        {% if pkgbase.Name.endswith(('-cvs', '-svn', '-git', '-hg', '-bzr', '-darcs')) %}
+            <p class="error">
+                {# TODO: This error is not yet translated. #}
+                {{
+                    "This seems to be a VCS package. Please do %snot%s flag "
+                    "it out-of-date if the package version in the AUR does "
+                    "not match the most recent commit. Flagging this package "
+                    "should only be done if the sources moved or changes in "
+                    "the PKGBUILD are required because of recent upstream "
+                    "changes." | tr | format("<strong>", "</strong>") | safe
+                }}
+            </p>
+        {% endif %}
+
         <p>
             {{
                 "Please do %snot%s use this form to report bugs. "
diff --git a/test/test_packages_routes.py b/test/test_packages_routes.py
index e2811a46..7eb4e532 100644
--- a/test/test_packages_routes.py
+++ b/test/test_packages_routes.py
@@ -1762,6 +1762,27 @@ def test_pkgbase_flag(client: TestClient, user: User, maintainer: User,
     assert pkgbase.Flagger is None
 
 
+def test_pkgbase_flag_vcs(client: TestClient, user: User, package: Package):
+    # Morph our package fixture into a VCS package (-git).
+    with db.begin():
+        package.PackageBase.Name += "-git"
+        package.Name += "-git"
+
+    cookies = {"AURSID": user.login(Request(), "testPassword")}
+    with client as request:
+        resp = request.get(f"/pkgbase/{package.PackageBase.Name}/flag",
+                           cookies=cookies)
+    assert resp.status_code == int(HTTPStatus.OK)
+
+    expected = ("This seems to be a VCS package. Please do "
+                "<strong>not</strong> flag it out-of-date if the package "
+                "version in the AUR does not match the most recent commit. "
+                "Flagging this package should only be done if the sources "
+                "moved or changes in the PKGBUILD are required because of "
+                "recent upstream changes.")
+    assert expected in resp.text
+
+
 def test_pkgbase_notify(client: TestClient, user: User, package: Package):
     pkgbase = package.PackageBase