diff --git a/collects/scribblings/guide/guide.scrbl b/collects/scribblings/guide/guide.scrbl
index 894f6e75fa..3beb695a30 100644
--- a/collects/scribblings/guide/guide.scrbl
+++ b/collects/scribblings/guide/guide.scrbl
@@ -16,6 +16,9 @@ Scheme. From @seclink["datatypes"]{Chapter 3} on, this guide dives
 into details---covering much of the PLT Scheme toolbox, but leaving
 precise details to @|MzScheme| and other reference manuals.
 
+@bold{This guide describes a potential future version of PLT Scheme.
+      It does not match the current implementation.}
+
 @table-of-contents[]
 
 @include-section["welcome.scrbl"]
diff --git a/collects/scribblings/reference/reference.scrbl b/collects/scribblings/reference/reference.scrbl
index e6f11aa7f5..c74df4b1b6 100644
--- a/collects/scribblings/reference/reference.scrbl
+++ b/collects/scribblings/reference/reference.scrbl
@@ -9,6 +9,9 @@ most prominent libraries. The companion manual
 a friendlier (though less precise and less complete) overview of the
 language.
 
+@bold{This reference describes a potential future version of PLT Scheme.
+      It does not match the current implementation.}
+
 @table-of-contents[]
 
 @include-section["model.scrbl"]