diff --git a/doc/misc/flymake.texi b/doc/misc/flymake.texi
index d3a76c8c4d7..d6c8778d785 100644
--- a/doc/misc/flymake.texi
+++ b/doc/misc/flymake.texi
@@ -858,7 +858,7 @@ Binding,,, elisp, The Emacs Lisp Reference Manual}) to be active.
                       ;;
                       (cl-loop
                        while (search-forward-regexp
-                              "^\\(?:.*.rb\\|-\\):\\([0-9]+\\): \\(.*\\)$"
+                              "^\\(?:.*\\.rb\\|-\\):\\([0-9]+\\): \\(.*\\)$"
                               nil t)
                        for msg = (match-string 2)
                        for (beg . end) = (flymake-diag-region
diff --git a/lisp/progmodes/ruby-mode.el b/lisp/progmodes/ruby-mode.el
index 210c8efb6fc..d9044c03aea 100644
--- a/lisp/progmodes/ruby-mode.el
+++ b/lisp/progmodes/ruby-mode.el
@@ -2516,7 +2516,7 @@ A slash character after any of these should begin a regexp."))
      (goto-char (point-min))
      (cl-loop
       while (search-forward-regexp
-             "^\\(?:.*.rb\\|-\\):\\([0-9]+\\): \\(.*\\)$"
+             "^\\(?:.*\\.rb\\|-\\):\\([0-9]+\\): \\(.*\\)$"
              nil t)
       for msg = (match-string 2)
       for (beg . end) = (flymake-diag-region
@@ -2625,7 +2625,7 @@ the gem \"rubocop\".  When t, it is used unconditionally."
          (goto-char (point-min))
          (cl-loop
           while (search-forward-regexp
-                 "^\\(?:.*.rb\\|-\\):\\([0-9]+\\):\\([0-9]+\\): \\(.*\\)$"
+                 "^\\(?:.*\\.rb\\|-\\):\\([0-9]+\\):\\([0-9]+\\): \\(.*\\)$"
                  nil t)
           for msg = (match-string 3)
           for (beg . end) = (flymake-diag-region