diff --git a/etc/DEBUG b/etc/DEBUG
index 3719c3e6f66..d7d6a0d2385 100644
--- a/etc/DEBUG
+++ b/etc/DEBUG
@@ -622,6 +622,15 @@ Setting a breakpoint in the function 'x_error_quitter' and looking at
 the backtrace when Emacs stops inside that function will show what
 code causes the X protocol errors.
 
+Note that the -xrm option may have no effect when you make an Emacs
+process invoked with the -nw option a server and want to trace X
+protocol errors from subsequent invocations of emacsclient in a GUI
+frame.  In that case calling the initial Emacs via
+
+emacs -nw --eval '(setq x-command-line-resources "emacs.synchronous: true")'
+
+should give more reliable results.
+
 Some bugs related to the X protocol disappear when Emacs runs in a
 synchronous mode.  To track down those bugs, we suggest the following
 procedure: