diff --git a/contrib/completion/git-prompt.sh b/contrib/completion/git-prompt.sh
index 54489080f8..dba928ed00 100644
--- a/contrib/completion/git-prompt.sh
+++ b/contrib/completion/git-prompt.sh
@@ -261,7 +261,7 @@ __git_ps1_colorize_gitstring ()
 
 eread ()
 {
-	f="$1"
+	local f="$1"
 	shift
 	test -r "$f" && read "$@" <"$f"
 }