diff --git a/collects/mzlib/inflate.ss b/collects/mzlib/inflate.ss
index 2b835b4159..e25157400e 100644
--- a/collects/mzlib/inflate.ss
+++ b/collects/mzlib/inflate.ss
@@ -271,19 +271,16 @@
       (READBITS n)))
   (define (READBITS n)
     (if (= buf-pos buf-max)
-        (if (and (buf-max . < . BUFFER-SIZE)
-                 (positive? buf-max))
-            (error 'inflate "unexpected end of file")
-            (begin
-              (when (positive? buf-max)
-                (read-bytes! buffer input-port 0 (- buf-max MAX-LOOKAHEAD))
-                ; (bytes-copy! buffer 0 buffer (- buf-max MAX-LOOKAHEAD) buf-max) 
-                (set! buf-pos MAX-LOOKAHEAD))
-              (let ([got (peek-bytes! buffer buf-pos input-port buf-pos BUFFER-SIZE)])
-                (if (eof-object? got)
-                    (error 'inflate "unexpected end of file")
-                    (set! buf-max (+ buf-pos got))))
-              (READBITS n)))
+        (begin
+          (when (positive? buf-max)
+            (read-bytes! buffer input-port 0 (- buf-max MAX-LOOKAHEAD))
+            ; (bytes-copy! buffer 0 buffer (- buf-max MAX-LOOKAHEAD) buf-max) 
+            (set! buf-pos MAX-LOOKAHEAD))
+          (let ([got (peek-bytes-avail! buffer buf-pos #f input-port buf-pos BUFFER-SIZE)])
+            (if (eof-object? got)
+                (error 'inflate "unexpected end of file")
+                (set! buf-max (+ buf-pos got))))
+          (READBITS n))
         (let ([v (bytes-ref buffer buf-pos)])
           (set! buf-pos (add1 buf-pos))
           (set! bb (+ bb (arithmetic-shift v bk)))