diff --git a/ice-9/threads.scm b/ice-9/threads.scm
index 1f360bf2b..ace701981 100644
--- a/ice-9/threads.scm
+++ b/ice-9/threads.scm
@@ -102,7 +102,7 @@
 		  futures)))))
 
 ;;; The following procedure is motivated by the common and important
-;;; case where a lot of work should be done (not too much) in parallel
+;;; case where a lot of work should be done, (not too much) in parallel,
 ;;; but the results need to be handled serially (for example when
 ;;; writing them to a file).
 ;;;