diff --git a/scsh/re.scm b/scsh/re.scm
index e44a005..9bbc802 100644
--- a/scsh/re.scm
+++ b/scsh/re.scm
@@ -95,8 +95,11 @@
   (let ((start (:optional maybe-start 0))
 	(start-vec (make-vector 10))
 	(end-vec (make-vector 10)))
-    (receive (err match?) (%string-match pattern string start
-					 start-vec end-vec)
+    (receive (err match?) (if (regexp? pattern)
+			      (%regexp-exec (%regexp:bytes pattern)
+					    string start start-vec end-vec)
+			      (%string-match pattern string start
+					     start-vec end-vec))
       (if err (error err string-match pattern string start)
 	  (and match? (make-regexp-match string start-vec end-vec))))))
 
@@ -158,6 +161,7 @@
 
 (define (regexp-substitute/global port re str . items)
   (let ((re (->regexp re))
+	(str-len (string-length str))
 	(range (lambda (start sv ev item)	; Return start & end of
 		 (cond ((integer? item)		; ITEM's range in STR.
 			(values (vector-ref sv item)
@@ -169,53 +173,78 @@
 	(num-posts (reduce (lambda (count item)
 			     (+ count (if (eq? item 'post) 1 0)))
 			   0 items)))
+
     (if (and port (< num-posts 2))
 
 	;; Output port case, with zero or one POST items.
 	(let recur ((start 0))
-	  (let ((match (regexp-exec re str start)))
-	    (if match
-		(let* ((sv (regexp-match:start match))
-		       (ev (regexp-match:end match)))
-		  (for-each (lambda (item)
-			      (cond ((string? item) (write-string item port))
-				    ((procedure? item) (write-string (item match) port))
-				    ((eq? 'post item) (recur (vector-ref ev 0)))
-				    (else (receive (si ei)
-					           (range start sv ev item)
-					    (write-string str port si ei)))))
-			    items))
+	  (if (<= start str-len)
+	      (let ((match (regexp-exec re str start)))
+		(if match
+		    (let* ((sv (regexp-match:start match))
+			   (ev (regexp-match:end match))
+			   (s (vector-ref sv 0))
+			   (e (vector-ref ev 0))
+			   (empty? (= s e)))
+		      (for-each (lambda (item)
+				  (cond ((string? item) (write-string item port))
 
-		(write-string str port start)))) ; No match.
+					((procedure? item) (write-string (item match) port))
 
+					((eq? 'post0 item)
+					 (if (and empty? (< s str-len))
+					     (write-char (string-ref str s) port)))
+
+					((eq? 'post item)
+					 (recur (if empty? (+ 1 e) e)))
+
+					(else (receive (si ei)
+						  (range start sv ev item)
+						(write-string str port si ei)))))
+				items))
+
+		    (write-string str port start))))) ; No match.
+
+	;; Either we're making a string, or >1 POST.
 	(let* ((pieces (let recur ((start 0))
-			 (let ((match (regexp-exec re str start))
-			       (cached-post #f))
-			   (if match
-			       (let* ((sv (regexp-match:start match))
-				      (ev (regexp-match:end match)))
-				 (reduce (lambda (pieces item)
-					   (cond ((string? item)
-						  (cons item pieces))
+			 (if (> start str-len) '()
+			     (let ((match (regexp-exec re str start))
+				   (cached-post #f))
+			       (if match
+				   (let* ((sv (regexp-match:start match))
+					  (ev (regexp-match:end match))
+					  (s (vector-ref sv 0))
+					  (e (vector-ref ev 0))
+					  (empty? (= s e)))
+				     (reduce (lambda (pieces item)
+					       (cond ((string? item)
+						      (cons item pieces))
 
-						 ((procedure? item)
-						  (cons (item match) pieces))
+						     ((procedure? item)
+						      (cons (item match) pieces))
 
-						 ((eq? 'post item)
-						  (if (not cached-post)
-						      (set! cached-post
-							    (recur (vector-ref ev 0))))
-						  (append cached-post pieces))
+						     ((eq? 'post0 item)
+						      (if (and empty? (< s str-len))
+							  (cons (string (string-ref str s))
+								pieces)
+							  pieces))
 
-						 (else (receive (si ei)
-							   (range start sv ev item)
-							 (cons (substring str si ei)
-							       pieces)))))
-					 '() items))
+						     ((eq? 'post item)
+						      (if (not cached-post)
+							  (set! cached-post
+								(recur (if empty? (+ e 1) e))))
+						      (append cached-post pieces))
 
-			       ;; No match. Return str[start,end].
-			       (list (if (zero? start) str 
-					 (substring str start (string-length str))))))))
+						     (else (receive (si ei)
+							       (range start sv ev item)
+							     (cons (substring str si ei)
+								   pieces)))))
+					     '() items))
+
+				   ;; No match. Return str[start,end].
+				   (list (if (zero? start) str 
+					     (substring str start (string-length str)))))))))
+			     
 	       (pieces (reverse pieces)))
 	  (if port (for-each (lambda (p) (write-string p port)) pieces)
 	      (apply string-append pieces))))))