diff --git a/t/t0021-conversion.sh b/t/t0021-conversion.sh
index 6c26fd829d8d9a08cb6cadfa013e0beae9b08dff..a839f4e0744cd9344a3d71a48fe2224a99750729 100755
--- a/t/t0021-conversion.sh
+++ b/t/t0021-conversion.sh
@@ -45,4 +45,40 @@ test_expect_success check '
 	test "z$id" = "z$embedded"
 '
 
+# If an expanded ident ever gets into the repository, we want to make sure that
+# it is collapsed before being expanded again on checkout
+test_expect_success expanded_in_repo '
+	{
+		echo "File with expanded keywords"
+		echo "\$Id\$"
+		echo "\$Id:\$"
+		echo "\$Id: 0000000000000000000000000000000000000000 \$"
+		echo "\$Id: NoSpaceAtEnd\$"
+		echo "\$Id:NoSpaceAtFront \$"
+		echo "\$Id:NoSpaceAtEitherEnd\$"
+		echo "\$Id: NoTerminatingSymbol"
+	} > expanded-keywords &&
+
+	{
+		echo "File with expanded keywords"
+		echo "\$Id: 4f21723e7b15065df7de95bd46c8ba6fb1818f4c \$"
+		echo "\$Id: 4f21723e7b15065df7de95bd46c8ba6fb1818f4c \$"
+		echo "\$Id: 4f21723e7b15065df7de95bd46c8ba6fb1818f4c \$"
+		echo "\$Id: 4f21723e7b15065df7de95bd46c8ba6fb1818f4c \$"
+		echo "\$Id: 4f21723e7b15065df7de95bd46c8ba6fb1818f4c \$"
+		echo "\$Id: 4f21723e7b15065df7de95bd46c8ba6fb1818f4c \$"
+		echo "\$Id: NoTerminatingSymbol"
+	} > expected-output &&
+
+	git add expanded-keywords &&
+	git commit -m "File with keywords expanded" &&
+
+	echo "expanded-keywords ident" >> .gitattributes &&
+
+	rm -f expanded-keywords &&
+	git checkout -- expanded-keywords &&
+	cat expanded-keywords &&
+	cmp expanded-keywords expected-output
+'
+
 test_done