diff --git a/elixir-mode.el b/elixir-mode.el
index 8e81fa60..df446aa5 100644
--- a/elixir-mode.el
+++ b/elixir-mode.el
@@ -185,7 +185,9 @@ for the Elixir programming language."
     `(
       (atoms . ,(rx ":"
                     (or
-                     (one-or-more (any "a-z" "A-Z" "_" "\"" "'"))
+                     (and
+                      (any "a-z" "A-Z" "_" "\"" "'")
+                      (zero-or-more (any "a-z" "A-Z" "0-9" "_" "\"" "'")))
                      (and "\"" (one-or-more (not (any "\""))) "\"")
                      (and "'" (one-or-more (not (any "'"))) "'"))))
       (builtin . ,(rx symbol-start
diff --git a/test/elixir-mode-font-test.el b/test/elixir-mode-font-test.el
index 856bb176..22b81169 100644
--- a/test/elixir-mode-font-test.el
+++ b/test/elixir-mode-font-test.el
@@ -124,11 +124,14 @@ end"
   :tags '(fontification atom syntax-table)
   (elixir-test-with-temp-buffer
       ":oriole
-:andale"
+:andale
+:ms2pid"
     (should (eq (elixir-test-face-at 3) 'elixir-atom-face))
     (should (eq (elixir-test-face-at 5) 'elixir-atom-face))
     (should (eq (elixir-test-face-at 10) 'elixir-atom-face))
-    (should (eq (elixir-test-face-at 13) 'elixir-atom-face))))
+    (should (eq (elixir-test-face-at 13) 'elixir-atom-face))
+    (should (eq (elixir-test-face-at 18) 'elixir-atom-face))
+    (should (eq (elixir-test-face-at 23) 'elixir-atom-face))))
 
 (ert-deftest elixir-mode-syntax-table/fontify-map-keys ()
   :tags '(fontification map syntax-table)