diff --git a/collects/scheme/private/string.ss b/collects/scheme/private/string.ss
index 51cad2399d..f1de9e5c71 100644
--- a/collects/scheme/private/string.ss
+++ b/collects/scheme/private/string.ss
@@ -109,7 +109,10 @@
   (define (bstring-length s)
     (if (bytes? s) (bytes-length s) (string-length s)))
   (define no-empty-edge-matches
-    (make-regexp-tweaker (lambda (rx) (format "(?=.)(?:~a)(?<=.)" rx))))
+    (make-regexp-tweaker (lambda (rx) 
+                           (if (bytes? rx)
+                               (bytes-append #"(?=.)(?:" rx #")(?<=.)")
+                               (format "(?=.)(?:~a)(?<=.)" rx)))))
   (define (bstring->no-edge-regexp name pattern)
     (if (or (regexp? pattern) (byte-regexp? pattern)
             (string? pattern) (bytes? pattern))
diff --git a/collects/tests/mzscheme/string.ss b/collects/tests/mzscheme/string.ss
index 8f4314bbac..7da4645772 100644
--- a/collects/tests/mzscheme/string.ss
+++ b/collects/tests/mzscheme/string.ss
@@ -75,6 +75,9 @@
   (t '("a" "b" "c") eof "[abc]" "a b c" 0)
   (t '("a" "b" "c") eof "[abc]" "a b c" 0 #f)
   (t '("a" "b" "c") eof "[abc]" "a b c" 0 5)
+  (for-each (lambda (cvt)
+              (test '(#"\x80" #"\x80") regexp-match* (cvt #"\x80") #"a\x80z\x80q"))
+            (list values byte-regexp byte-pregexp))
   ;; --------------------
   (t regexp-match-positions*)
   (t '((1 . 2) (3 . 4) (5 . 6)) eof "[abc]" " a b c ")
@@ -92,6 +95,9 @@
   (t '((0 . 1) (2 . 3) (4 . 5)) eof "[abc]" "a b c" 0)
   (t '((0 . 1) (2 . 3) (4 . 5)) eof "[abc]" "a b c" 0 #f)
   (t '((0 . 1) (2 . 3) (4 . 5)) eof "[abc]" "a b c" 0 5)
+  (for-each (lambda (cvt)
+              (test '((1 . 2) (3 . 4)) regexp-match-positions* (cvt #"\x80") #"a\x80z\x80q"))
+            (list values byte-regexp byte-pregexp))
   ;; --------------------
   (t regexp-split)
   (t '("1" "2" "3" "4") eof "[abc]" "1a2b3c4")
@@ -109,6 +115,9 @@
   (t '("" "1" "2" "") eof   "[abc]" "a1b2c" 0)
   (t '("" "1" "2" "") eof   "[abc]" "a1b2c" 0 #f)
   (t '("" "1" "2" "") eof   "[abc]" "a1b2c" 0 5)
+  (for-each (lambda (cvt)
+              (test '(#"" #"a" #"z" #"q" #"") regexp-split (cvt #"\x80") #"\x80a\x80z\x80q\x80"))
+            (list values byte-regexp byte-pregexp))
   ;; --------------------
   (t regexp-match-peek-positions*)
   (err/rt-test (regexp-match-peek-positions* "[abc]" "a b c"))