1 files changed, 1 insertions, 1 deletions

diff --git a/lisp/progmodes/prog-mode.el b/lisp/progmodes/prog-mode.el
index 3b850f3305b..407466932d9 100644
--- a/lisp/progmodes/prog-mode.el
+++ b/lisp/progmodes/prog-mode.el
@@ -67,7 +67,7 @@ Regexp match data 0 points to the chars."
   (let* ((start (match-beginning 0))
          (end (match-end 0))
          (syntaxes (if (eq (char-syntax (char-after start)) ?w)
-                       '(?w) '(?. ?\\)))
+                       '(?w ?_) '(?. ?\\)))
          match)
     (if (or (memq (char-syntax (or (char-before start) ?\s)) syntaxes)
             (memq (char-syntax (or (char-after end) ?\s)) syntaxes)