diff --git a/gash/environment.scm b/gash/environment.scm
index 6a8f141..4be796a 100644
--- a/gash/environment.scm
+++ b/gash/environment.scm
@@ -56,6 +56,9 @@
             sh:exit
             *fd-count*
             fd->current-port
+            current-0-port
+            current-1-port
+            current-2-port
             get-last-job
             set-last-job!
             reap-child-processes!))
@@ -419,6 +422,21 @@ status.  If not called from within @code{call-with-return}, return
 
 (define *fd-count* 10)
 
+(define current-0-port
+  (case-lambda
+    (() (current-input-port))
+    ((value) (set-current-input-port value))))
+
+(define current-1-port
+  (case-lambda
+    (() (current-output-port))
+    ((value) (set-current-output-port value))))
+
+(define current-2-port
+  (case-lambda
+    (() (current-error-port))
+    ((value) (set-current-error-port value))))
+
 (define current-3-port (make-parameter #f))
 (define current-4-port (make-parameter #f))
 (define current-5-port (make-parameter #f))
@@ -428,9 +446,9 @@ status.  If not called from within @code{call-with-return}, return
 (define current-9-port (make-parameter #f))
 
 (define fd->current-port
-  (let ((cps (vector current-input-port
-                     current-output-port
-                     current-error-port
+  (let ((cps (vector current-0-port
+                     current-1-port
+                     current-2-port
                      current-3-port
                      current-4-port
                      current-5-port
diff --git a/gash/shell.scm b/gash/shell.scm
index 3611067..2bf724c 100644
--- a/gash/shell.scm
+++ b/gash/shell.scm
@@ -241,8 +241,15 @@ if it is our responsibility to close the port."
                      (#f (set-status! 1)
                          (errexit))
                      ((parameter port close?)
-                      (parameterize ((parameter port))
-                        (thunk))
+                      (cond
+                       ((eq? parameter current-0-port)
+                        (with-input-from-port port thunk))
+                       ((eq? parameter current-1-port)
+                        (with-output-to-port port thunk))
+                       ((eq? parameter current-2-port)
+                        (with-error-to-port port thunk))
+                       (else
+                        (parameterize ((parameter port)) (thunk))))
                       (cond
                        (close? (close-port port))
                        ((output-port? port) (force-output port)))))))
@@ -311,9 +318,10 @@ be closed in the new process."
                    (when close (close-port close))
                    (let ((in (or in (current-input-port)))
                          (out (or out (current-output-port))))
-                     (parameterize ((current-input-port in)
-                                    (current-output-port out))
-                       (thunk)))))
+                     (with-input-from-port in
+                       (lambda ()
+                         (with-output-to-port out
+                           thunk))))))
          (pid (%subshell thunk*)))
     (when in (close-port in))
     (when out (close-port out))