diff --git a/src/coding.c b/src/coding.c
index baacf26db0d..1cc75fdae16 100644
--- a/src/coding.c
+++ b/src/coding.c
@@ -7825,8 +7825,7 @@ associated with each coding-category one by one in this order.  When
 one algorithm agrees with a byte sequence of source text, the coding
 system bound to the corresponding coding-category is selected.
 
-When you modify this variable, `update-coding-systems-internal' must
-be called.  */);
+Don't modify this variable directly, but use `set-coding-category'.  */);
   {
     int i;