diff --git a/src/ChangeLog b/src/ChangeLog
index 52581be2863..854c4987be5 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,7 @@
+2011-10-25  Paul Eggert  <eggert@cs.ucla.edu>
+
+	* dispextern.h (Fcontrolling_tty_p): New decl (Bug#6649 part 2).
+
 2011-10-25  Stefan Monnier  <monnier@iro.umontreal.ca>
 
 	* keyboard.c (test_undefined): New function (bug#9751).
diff --git a/src/dispextern.h b/src/dispextern.h
index dd5f67d2d10..5c60a5499da 100644
--- a/src/dispextern.h
+++ b/src/dispextern.h
@@ -3346,6 +3346,7 @@ extern int tty_capable_p (struct tty_display_info *, unsigned, unsigned long, un
 extern void set_tty_color_mode (struct tty_display_info *, struct frame *);
 extern struct terminal *get_named_tty (const char *);
 EXFUN (Ftty_type, 1);
+EXFUN (Fcontrolling_tty_p, 1);
 extern void create_tty_output (struct frame *);
 extern struct terminal *init_tty (const char *, const char *, int);
 extern void tty_append_glyph (struct it *);