diff --git a/lisp/files.el b/lisp/files.el
index d42154cf8a2..edbeb43e9b9 100644
--- a/lisp/files.el
+++ b/lisp/files.el
@@ -3114,6 +3114,8 @@ since only a single case-insensitive search through the alist is made."
     ;; Bash builtin 'fc' creates a temp file named "bash-fc.XXXXXX"
     ;; to edit shell commands from its history list.
     ("/bash-fc\\.[0-9A-Za-z]\\{6\\}\\'" . sh-mode)
+    ;; A login sh first attempts to read /etc/profile.
+    ("\\`/etc/profile\\'" . sh-mode)
     ("/PKGBUILD\\'" . sh-mode)
     ("\\(/\\|\\`\\)\\.\\(bash_\\(profile\\|history\\|log\\(in\\|out\\)\\)\\|z?log\\(in\\|out\\)\\)\\'" . sh-mode)
     ("\\(/\\|\\`\\)\\.\\(shrc\\|zshrc\\|m?kshrc\\|bashrc\\|t?cshrc\\|esrc\\)\\'" . sh-mode)