diff --git a/runtime/doc/gui.txt b/runtime/doc/gui.txt
index 071de9c..4fdfc0f 100644
--- a/runtime/doc/gui.txt
+++ b/runtime/doc/gui.txt
@@ -1,4 +1,4 @@
-*gui.txt*       For Vim version 9.1.  Last change: 2024 Jul 17
+*gui.txt*       For Vim version 9.1.  Last change: 2024 Nov 07
 
 
 		  VIM REFERENCE MANUAL    by Bram Moolenaar
@@ -474,6 +474,8 @@
 register is the same as the "* register.  Thus you can yank to and paste the
 selection without prepending "* to commands.
 
+See also |W23|.
+
 ==============================================================================
 5. Menus						*menus*
 
diff --git a/runtime/doc/gui_x11.txt b/runtime/doc/gui_x11.txt
index dbd4b10..0658bfa 100644
--- a/runtime/doc/gui_x11.txt
+++ b/runtime/doc/gui_x11.txt
@@ -1,4 +1,4 @@
-*gui_x11.txt*   For Vim version 9.1.  Last change: 2024 Apr 22
+*gui_x11.txt*   For Vim version 9.1.  Last change: 2024 Nov 11
 
 
 		  VIM REFERENCE MANUAL    by Bram Moolenaar
@@ -708,6 +708,14 @@
 Note that the text in the "+ register remains available when making a Visual
 selection, which makes other text available in the "* register.  That allows
 overwriting selected text.
+
+								*W23*
+When you are yanking into the "* or "+ register and Vim cannot establish a
+connection to the X11 selection (or clipboard), it will use register 0 and
+output a warning:
+
+  Warning: Clipboard register not available, using register 0 ~
+
 							*x11-cut-buffer*
 There are, by default, 8 cut-buffers: CUT_BUFFER0 to CUT_BUFFER7.  Vim only
 uses CUT_BUFFER0, which is the one that xterm uses by default.
diff --git a/runtime/doc/tags b/runtime/doc/tags
index d38c895..00d65eb 100644
--- a/runtime/doc/tags
+++ b/runtime/doc/tags
@@ -5818,6 +5818,7 @@
 W20	if_pyth.txt	/*W20*
 W21	if_pyth.txt	/*W21*
 W22	userfunc.txt	/*W22*
+W23	gui_x11.txt	/*W23*
 WORD	motion.txt	/*WORD*
 WSL	os_win32.txt	/*WSL*
 WWW	intro.txt	/*WWW*