diff --git a/src/cmds.c b/src/cmds.c
index 99e436e65c1..e9dee5ed2e3 100644
--- a/src/cmds.c
+++ b/src/cmds.c
@@ -477,7 +477,8 @@ internal_self_insert (int c, EMACS_INT n)
   if ((CHAR_TABLE_P (Vauto_fill_chars)
        ? !NILP (CHAR_TABLE_REF (Vauto_fill_chars, c))
        : (c == ' ' || c == '\n'))
-      && !NILP (BVAR (current_buffer, auto_fill_function)))
+      && !NILP (BVAR (current_buffer, auto_fill_function))
+      && n > 0)
     {
       Lisp_Object auto_fill_result;
 
diff --git a/test/src/cmds-tests.el b/test/src/cmds-tests.el
index a02c36868ca..8c0e4706e3c 100644
--- a/test/src/cmds-tests.el
+++ b/test/src/cmds-tests.el
@@ -40,5 +40,13 @@
     (let ((shortage (forward-line (+ 2 most-positive-fixnum))))
       (should (= shortage (1+ most-positive-fixnum))))))
 
+(ert-deftest self-insert-zero-newlines ()
+  "Test `self-insert-command' with arguments which used to cause a crash."
+  (with-temp-buffer
+    (let* ((pt nil)
+           (auto-fill-function (lambda () (setq pt (point)))))
+      (self-insert-command 0 10)
+      (should-not (equal pt 0)))))
+
 (provide 'cmds-tests)
 ;;; cmds-tests.el ends here