From emacs -Q, load the attached file. Then use the following recipe to trigger the error: M-x goto-line RET 334 RET TAB After the tab, I get the error: c-just-after-func-arglist-p: Wrong type argument: integer-or-marker-p, nil The backtrace is: Debugger entered--Lisp error: (wrong-type-argument integer-or-marker-p nil) c-forward-decl-or-cast-1(8107 top nil) c-just-after-func-arglist-p(8114) c-guess-basic-syntax() c-indent-line() #[0 "\301\302 !\210\303>\203;\212\304 \210o\203\305\202'\304\305!\210\306\307!\203%\305\202'\310 )i\310 X\2035\311!\202:\212\311!)\207 \207" [indent-line-function syntax-propertize line-end-position (indent-relative indent-relative-maybe) beginning-of-line 0 looking-at "[ ]*$" current-indentation indent-line-to] 3 2103790 nil]() c-indent-command(nil) c-indent-line-or-region(nil nil) funcall-interactively(c-indent-line-or-region nil nil) call-interactively(c-indent-line-or-region nil nil) command-execute(c-indent-line-or-region)