diff --git a/implementations/racket/preserves/preserves/float-bytes.rkt b/implementations/racket/preserves/preserves/float-bytes.rkt
new file mode 100644
index 0000000..b0d43b6
--- /dev/null
+++ b/implementations/racket/preserves/preserves/float-bytes.rkt
@@ -0,0 +1,24 @@
+#lang racket/base
+;; Conversion between binary32 and binary64 big-endian external format (byte-vectors) and
+;; internal double-precision floating-point numbers, with special attention paid to
+;; preservation of the quiet/signaling bit of NaNs, which otherwise is frequently disturbed by
+;; hardware-level conversion between single and double precision.
+
+(provide bytes->float
+         float->bytes
+         bytes->double
+         double->bytes)
+
+(require "float.rkt")
+
+(define (bytes->float bs)
+  (float (floating-point-bytes->real bs #t 0 4)))
+
+(define (float->bytes v)
+  (real->floating-point-bytes (float-value v) 4 #t))
+
+(define (bytes->double bs)
+  (floating-point-bytes->real bs #t 0 8))
+
+(define (double->bytes v)
+  (real->floating-point-bytes v 8 #t))
diff --git a/implementations/racket/preserves/preserves/jelly.rkt b/implementations/racket/preserves/preserves/jelly.rkt
index 0895429..6ab8ef1 100644
--- a/implementations/racket/preserves/preserves/jelly.rkt
+++ b/implementations/racket/preserves/preserves/jelly.rkt
@@ -8,8 +8,8 @@
 ;;---------------------------------------------------------------------------
 ;; Representing values
 
+(require "float.rkt" "float-bytes.rkt")
 (struct record (label fields) #:transparent)
-(struct float (value) #:transparent) ;; a marker for single-precision I/O
 (struct annotated (annotations item) #:transparent)
 (struct embedded (value) #:transparent)
 
@@ -23,8 +23,8 @@
       (match (next-byte)
         [#x80 #f]
         [#x81 #t]
-        [#x82 (float (floating-point-bytes->real (next-bytes 4) #t 0 4))]
-        [#x83 (floating-point-bytes->real (next-bytes 8) #t 0 8)]
+        [#x82 (bytes->float (next-bytes 4))]
+        [#x83 (bytes->double (next-bytes 8))]
         [#x84 '#:end]
         [#x85 (let ((a (next)))
                 (match (next)
@@ -80,8 +80,8 @@
     (match v
       [#f (write-byte #x80 out-port)]
       [#t (write-byte #x81 out-port)]
-      [(float v) (write-byte #x82 out-port) (output-bytes (real->floating-point-bytes v 4 #t))]
-      [(? flonum?) (write-byte #x83 out-port) (output-bytes (real->floating-point-bytes v 8 #t))]
+      [(float _) (write-byte #x82 out-port) (output-bytes (float->bytes v))]
+      [(? flonum?) (write-byte #x83 out-port) (output-bytes (double->bytes v))]
 
       [(annotated as v)
        (for [(a (in-list as))] (write-byte #x85 out-port) (output a))
diff --git a/implementations/racket/preserves/preserves/read-binary.rkt b/implementations/racket/preserves/preserves/read-binary.rkt
index 0ec1f28..9459adb 100644
--- a/implementations/racket/preserves/preserves/read-binary.rkt
+++ b/implementations/racket/preserves/preserves/read-binary.rkt
@@ -7,6 +7,7 @@
 (require "record.rkt")
 (require "embedded.rkt")
 (require "float.rkt")
+(require "float-bytes.rkt")
 (require "annotation.rkt")
 (require "varint.rkt")
 (require racket/set)
@@ -70,8 +71,8 @@
       (match lead-byte
         [#x80 #f]
         [#x81 #t]
-        [#x82 (float (floating-point-bytes->real (next-bytes 4) #t 0 4))]
-        [#x83 (floating-point-bytes->real (next-bytes 8) #t 0 8)]
+        [#x82 (bytes->float (next-bytes 4))]
+        [#x83 (bytes->double (next-bytes 8))]
         [#x84 '#:end]
         [#x85 (let ((a (next)))
                 (if read-annotations?
diff --git a/implementations/racket/preserves/preserves/read-text.rkt b/implementations/racket/preserves/preserves/read-text.rkt
index f634af6..b3e20c2 100644
--- a/implementations/racket/preserves/preserves/read-text.rkt
+++ b/implementations/racket/preserves/preserves/read-text.rkt
@@ -10,6 +10,7 @@
 (require "read-binary.rkt")
 (require "record.rkt")
 (require "float.rkt")
+(require "float-bytes.rkt")
 (require syntax/readerr)
 (require (only-in file/sha1 hex-string->bytes))
 (require (only-in net/base64 base64-decode))
@@ -82,8 +83,8 @@
              [#\" (read-literal-binary)]
              [#\x (match (next-char)
                     [#\" (read-hex-binary '())]
-                    [#\f (float (read-hex-float 4))]
-                    [#\d (read-hex-float 8)]
+                    [#\f (read-hex-float 'float)]
+                    [#\d (read-hex-float 'double)]
                     [c (parse-error "Invalid #x syntax: ~v" c)])]
              [#\[ (read-base64-binary '())]
              [#\! (embedded (decode-embedded (next)))]
@@ -228,13 +229,15 @@
   ;;---------------------------------------------------------------------------
   ;; Hex-encoded floating point numbers
 
-  (define (read-hex-float byte-count)
+  (define (read-hex-float precision)
     (unless (eqv? (next-char) #\")
       (parse-error "Missing open-double-quote in hex-encoded floating-point number"))
     (define bs (read-hex-binary '()))
-    (unless (= (bytes-length bs) byte-count)
+    (unless (= (bytes-length bs) (match precision ['float 4] ['double 8]))
       (parse-error "Incorrect number of bytes in hex-encoded floating-point number"))
-    (floating-point-bytes->real bs #t 0 byte-count))
+    (match precision
+      ['float (bytes->float bs)]
+      ['double (bytes->double bs)]))
 
   ;;---------------------------------------------------------------------------
   ;; Base64-encoded ByteStrings
diff --git a/implementations/racket/preserves/preserves/write-binary.rkt b/implementations/racket/preserves/preserves/write-binary.rkt
index 664b433..d84b559 100644
--- a/implementations/racket/preserves/preserves/write-binary.rkt
+++ b/implementations/racket/preserves/preserves/write-binary.rkt
@@ -8,6 +8,7 @@
 (require "record.rkt")
 (require "embedded.rkt")
 (require "float.rkt")
+(require "float-bytes.rkt")
 (require "annotation.rkt")
 (require "varint.rkt")
 (require "object-id.rkt")
@@ -86,12 +87,12 @@
       [#f (output-byte #x80)]
       [#t (output-byte #x81)]
 
-      [(float v)
+      [(float _)
        (output-byte #x82)
-       (output-bytes (real->floating-point-bytes v 4 #t))]
+       (output-bytes (float->bytes v))]
       [(? flonum?)
        (output-byte #x83)
-       (output-bytes (real->floating-point-bytes v 8 #t))]
+       (output-bytes (double->bytes v))]
 
       [(annotated as _ v)
        (when write-annotations?
diff --git a/implementations/racket/preserves/preserves/write-text.rkt b/implementations/racket/preserves/preserves/write-text.rkt
index ba59d8f..84c3aa1 100644
--- a/implementations/racket/preserves/preserves/write-text.rkt
+++ b/implementations/racket/preserves/preserves/write-text.rkt
@@ -12,6 +12,7 @@
 (require "embedded.rkt")
 (require "annotation.rkt")
 (require "float.rkt")
+(require "float-bytes.rkt")
 (require "record.rkt")
 (require "object-id.rkt")
 (require racket/dict)
@@ -134,12 +135,14 @@
               (write-binary-stringlike v)
               (write-binary-base64 outer-distance v)))))
 
-  (define (write-float v byte-count hextype suffix)
+  (define (write-float v precision)
     (if (or (nan? v) (infinite? v))
         (! "#x~a\"~a\""
-           hextype
-           (bytes->hex-string (real->floating-point-bytes v byte-count #t)))
-        (! "~v~a" v suffix)))
+           (match precision ['float "f"] ['double "d"])
+           (bytes->hex-string (match precision
+                                ['float (float->bytes (float v))]
+                                ['double (double->bytes v)])))
+        (! "~v~a" v (match precision ['float "f"] ['double ""]))))
 
   (define (write-value distance v)
     (match v
@@ -152,8 +155,8 @@
        (write-value distance item)]
       [#f (! "#f")]
       [#t (! "#t")]
-      [(float v) (write-float v 4 "f" "f")]
-      [(? flonum?) (write-float v 8 "d" "")]
+      [(float v) (write-float v 'float)]
+      [(? flonum?) (write-float v 'double)]
       [(? integer? x) (! "~v" v)]
       [(? string?)
        (! "\"")