diff --git a/lib/thread-safe.lisp b/lib/thread-safe.lisp
index b464265..ca8ab9b 100644
--- a/lib/thread-safe.lisp
+++ b/lib/thread-safe.lisp
@@ -2,18 +2,26 @@
 ;;; SIMPLE AND SAFE SLIME MODE
 ;;; ==========================
 ;;;
-;;; Loading this file before loading EQL code guarantees running EQL functions in the GUI thread.
+;;; Loading this file before calling any EQL function (involving the UI)
+;;; guarantees running EQL functions on the UI thread.
 ;;;
-;;; This means that we don't need a Slime REPL-hook, making it safe to evaluate any EQL code in
-;;; Slime, both on the REPL and using 'eval-region'.
+;;; This means that we don't need a Slime REPL-hook, making it safe to evaluate
+;;; any EQL code in Slime, both on the REPL and using 'eval-region'.
 ;;;
-;;; The only drawback is a little more consing for every EQL function call, but allowing to safely
-;;; call GUI functions from any ECL thread.
+;;; The only drawback is a little more consing for every EQL function call, but
+;;; allowing to safely call UI functions from any ECL thread.
 ;;;
-;;; Note also that wrapping functions in QRUN* is basically the same as a direct call, if called
-;;; from the ECL main thread (GUI thread), so it will add almost no overhead.
-;;; Since most EQL function calls are driven by the Qt event loop anyway, you won't even notice
-;;; the presence of macro QRUN* (performance wise).
+;;; Note also that wrapping functions in QRUN* (like done here, see below) is
+;;; basically the same as a direct call, if called from the ECL main thread (UI
+;;; thread), so it will add almost no overhead. Since most EQL function calls
+;;; are driven by the Qt event loop anyway, you won't even notice the presence
+;;; of macro QRUN* (performance wise).
+;;;
+;;; N.B: If you want to start/run EQL in a thread (other than the UI one), you
+;;; just need to add this file to your project. Note that any EQL function call
+;;; will now do a thread switch internally, so you may experience (much) slower
+;;; execution. See also comment in 'examples/X-extras/primes-thread.lisp' about
+;;; manually wrapping repeated calls in macro QRUN*.
 ;;;
 
 (in-package :eql)