diff --git a/README.org b/README.org
index 728a346..6e8c45a 100644
--- a/README.org
+++ b/README.org
@@ -26,6 +26,7 @@
     - [[#org-mode][Org Mode]]
     - [[#projectile][Projectile]]
     - [[#prettier-formatter][Prettier Formatter]]
+    - [[#file-extension-mode-association][File Extension Mode Association]]
   - [[#packagesel][packages.el]]
     - [[#packages][Packages]]
 
@@ -427,6 +428,12 @@ If you use =org= and don't want your org files in the default location below, ch
 (add-hook! 'web-mode-hook 'prettier-js-mode)
 #+END_SRC
 
+*** File Extension Mode Association
+
+#+BEGIN_SRC emacs-lisp :tangle config.el
+(add-to-list 'auto-mode-alist '("\\.m\\'" . octave-mode))
+#+END_SRC
+
 ** packages.el
 
 To install a package with Doom you must declare them here and run =doom sync= on the command line, then restart Emacs for the changes to take effect -- or use =M-x doom/reload=.
diff --git a/config.el b/config.el
index 7d5857d..e2587f1 100644
--- a/config.el
+++ b/config.el
@@ -43,3 +43,5 @@
 (setq projectile-project-search-path '("~/Projects/" "~/.config/"))
 
 (add-hook! 'web-mode-hook 'prettier-js-mode)
+
+(add-to-list 'auto-mode-alist '("\\.m\\'" . octave-mode))