Use matching single quotes in messages.
diff --git a/regress/open_zip64_ok.test b/regress/open_zip64_ok.test
index ab39c9a..ac33f9a 100644
--- a/regress/open_zip64_ok.test
+++ b/regress/open_zip64_ok.test
@@ -3,4 +3,4 @@
 args test.zip
 return 0
 file test.zip zip64.zip zip64.zip
-stdout opening `test.zip' succeeded, 1 entries
+stdout opening 'test.zip' succeeded, 1 entries