diff --git a/flang/docs/Extensions.md b/flang/docs/Extensions.md
index 17d01d81d329..f2770f0a7271 100644
--- a/flang/docs/Extensions.md
+++ b/flang/docs/Extensions.md
@@ -483,6 +483,9 @@ end
   are to the same value.  Distinct initializations remain errors.
 * A pointer component that has no default initialization or explicit value
   in a structure constructor is defaulted to `NULL()`.
+* Multiple specifications of a prefix-spec on the same procedure are allowed,
+  with a warning.  C1552 (F2023) specifies that at most one of each shall be
+  present.
 * An assumed-rank entity is an acceptable `NAMELIST` group item.
 * A named constant (`PARAMETER`) may appear as a `namelist-group-object` in a
   `NAMELIST` statement.  The Fortran standard requires namelist group objects