diff --git a/describe/float-test-extended.rkt b/describe/float-test-extended.rkt
deleted file mode 100644
index 7923dd3..0000000
--- a/describe/float-test-extended.rkt
+++ /dev/null
@@ -1,27 +0,0 @@
-#lang racket/base
-
-(require racket/extflonum
-         "main.rkt")
-
-(printf "--- Using literals (extended precision) ---~n")
-(describe 0.1t0)
-(describe 0.2t0)
-(describe 0.3t0)
-(describe 0.4t0)
-(describe 0.5t0)
-(describe 0.6t0)
-(describe 0.7t0)
-(describe 0.8t0)
-(describe 0.9t0)
-(describe 1.0t0)
-
-(printf "--- Using summation (extended precision) ---~n")
-(for/fold ((sum 0.0t0))
-          ((i (in-range 10)))
-  (define new-sum (extfl+ sum 0.1t0))
-  (describe new-sum)
-  new-sum)
-
-(printf "--- Using product (single precision) ---~n")
-(for ((i (in-range 1 11)))
-  (describe (extfl* (->extfl i) 0.1t0)))
diff --git a/describe/main.rkt b/describe/main.rkt
index bd25a73..19ddbbe 100644
--- a/describe/main.rkt
+++ b/describe/main.rkt
@@ -71,7 +71,6 @@
 ;;; 2.0.1    09/26/13 Added bigfloat support to float->string. (MDW)
 
 (require racket/contract/base
-         racket/extflonum
          racket/math
          racket/mpair)
 
@@ -307,7 +306,7 @@
          (format "~s is an exact number" z))))
 
 ;;; (float->string x) -> string?
-;;;   x : (or/c flonum? single-flonum? extflonum? bigfloat?)
+;;;   x : (or/c flonum? single-flonum? bigfloat?)
 ;;; Returns a string with the exact decimal representation of x. This is only
 ;;; guaranteed for floats - single, double, or extended precision, which are
 ;;; never repeating decimals.
@@ -403,6 +402,16 @@
         (else
          (format "~s is a number" z))))
 
+
+;;; 201223 Racket CS update
+;;; Racket CS does not support extflonums
+;;; so we remove racket/extflonum from depednencies
+;;; and make the extflonum functions into no-ops
+(define (extflonum? x) #false)
+(define (extfl< . xs) #false)
+(define (extfl> . xs) #false)
+(define (extfl->exact x) 0)
+
 ;;; (extflonum-description x) -> string
 ;;;   x : extflonum?
 ;;; Returns a string describing the extended precision floating point number, x.
@@ -843,7 +852,7 @@
  (integer->string
   (-> exact-integer? string?))
  (float->string
-  (-> (or/c flonum? single-flonum? extflonum?) string?))
+  (-> (or/c flonum? single-flonum?) string?))
  (description
   (-> any/c string?))
  (describe
diff --git a/describe/scribblings/describe.scrbl b/describe/scribblings/describe.scrbl
index 32e6142..4311986 100644
--- a/describe/scribblings/describe.scrbl
+++ b/describe/scribblings/describe.scrbl
@@ -14,7 +14,7 @@
 This library provides functions to describe Racket objects. Currently, the following types of objects are described:
 
 
-@margin-note{This is not the official version of Describe. It is the 1.5 version from PLaneT, retooled to use Racket's new package system, and with bigfloat support disabled (because of bugs related to v.5.3.x compatability.) The canonical version of Describe is on the @link["http://planet.racket-lang.org/display.ss?package=describe.plt&owner=williams" "PLaneT server"]. — MB}
+@margin-note{This is not the official version of Describe. It is the 1.5 version from PLaneT, retooled to use Racket's new package system, and with bigfloatsdisabled (because of incompatability with v.5.3) and extflonums disabled (because of incompatability with Racket CS). The canonical version of Describe is on the @link["http://planet.racket-lang.org/display.ss?package=describe.plt&owner=williams" "PLaneT server"]. — MB}
 
 @itemize{
   @item{Booleans}