1 files changed, 1 insertions, 1 deletions

diff --git a/lisp/progmodes/grep.el b/lisp/progmodes/grep.el
index ecc386404c6..433c2705cd5 100644
--- a/lisp/progmodes/grep.el
+++ b/lisp/progmodes/grep.el
@@ -753,7 +753,7 @@ This command shares argument histories with \\[lgrep] and \\[grep-find]."
                               " " find-name-arg " "
                               (mapconcat #'shell-quote-argument
                                          (split-string files)
-                                         " -o " find-name-arg " ")
+                                         (concat " -o " find-name-arg " "))
                               " "
                               (shell-quote-argument ")"))
                        dir