diff --git a/src/os/error_plan9.go b/src/os/error_plan9.go
index 0d76a66e45..b82bf0dea3 100644
--- a/src/os/error_plan9.go
+++ b/src/os/error_plan9.go
@@ -5,7 +5,7 @@
 package os
 
 func isExist(err error) bool {
-	return checkErrMessageContent(err, " exists", " is a directory")
+	return checkErrMessageContent(err, "exists", "is a directory")
 }
 
 func isNotExist(err error) bool {