diff --git a/ciel.asd b/ciel.asd
index ff177dd..ba64fa9 100644
--- a/ciel.asd
+++ b/ciel.asd
@@ -105,7 +105,8 @@
                :secret-values
 
                ;; other utilities
-               :progressons  ;; simple progress bar. Not in Quicklisp as of <2024-08-30>.
+               :progressons  ;; no deps. Simple progress bar. Not in Quicklisp as of <2024-08-30>.
+               :termp  ;; no deps. Are we in a dumb terminal like Slime's REPL?
 
                ;;;
                ;;; Language extensions.
diff --git a/docs/libraries.md b/docs/libraries.md
index ec9f534..7a68646 100644
--- a/docs/libraries.md
+++ b/docs/libraries.md
@@ -902,6 +902,9 @@ As you can see, it needs a manual `step!` to make it progress.
 
 > WARN: progressons in its present form adds significant overhead. You shouldn't use it with a large dataset.
 
+Use [termp](https://github.com/vindarel/termp) if you want to check
+wether you are inside a dumb terminal, like Slime's REPL, or a real
+one. This check is done by looking at the `TERM` environment variable.
 
 ## Development