diff --git a/src/nano.c b/src/nano.c
index f9978941..308a47e1 100644
--- a/src/nano.c
+++ b/src/nano.c
@@ -1388,7 +1388,7 @@ bool wanted_to_move(void (*func)(void))
 }
 
 /* Return TRUE when the given function makes a change -- no good for view mode. */
-bool changes_something(const void *f)
+bool changes_something(functionptrtype f)
 {
 	return (f == do_savefile || f == do_writeout || f == do_enter || f == do_tab ||
 			f == do_delete || f == do_backspace || f == cut_text || f == paste_text ||
diff --git a/src/prototypes.h b/src/prototypes.h
index 530c4b9f..df46e979 100644
--- a/src/prototypes.h
+++ b/src/prototypes.h
@@ -427,7 +427,7 @@ void terminal_init(void);
 void confirm_margin(void);
 #endif
 void unbound_key(int code);
-bool changes_something(const void *f);
+bool changes_something(functionptrtype f);
 void inject(char *burst, size_t count);
 
 /* Most functions in prompt.c. */