diff --git a/lisp/textmodes/fill.el b/lisp/textmodes/fill.el
index ce83ad737b1..8422f0e1dd2 100644
--- a/lisp/textmodes/fill.el
+++ b/lisp/textmodes/fill.el
@@ -50,10 +50,11 @@ A value of nil means that any change in indentation starts a new paragraph."
 (put 'colon-double-space 'safe-local-variable 'booleanp)
 
 (defcustom fill-separate-heterogeneous-words-with-space nil
-  "Non-nil means that use a space to separate words of different kind.
-This will be done with a word in the end of a line and a word in the
-beginning of the next line when concatenating them for filling those
-lines.  Whether to use a space is up to how the words are categorized."
+  "Non-nil means to use a space to separate words of a different kind.
+This will be done with a word in the end of a line and a word in
+the beginning of the next line when concatenating them for
+filling those lines.  Whether to use a space depends on how the
+words are categorized."
   :type 'boolean
   :group 'fill
   :version "26.1")