diff --git a/ice-9/ChangeLog b/ice-9/ChangeLog
index 917fa7b22..c496f8e91 100644
--- a/ice-9/ChangeLog
+++ b/ice-9/ChangeLog
@@ -1,3 +1,13 @@
+2001-06-29  Neil Jerram  <neil@ossau.uklinux.net>
+
+	Changes to support tracing other than inside the repl-stack that
+	is set up by the REPL code in boot-9.scm.
+	
+	* debug.scm (trace-entry, trace-exit): Conditionalize tracing on
+	whether the current stack id is in `traced-stack-ids'.
+	(traced-stack-ids, trace-all-stacks?, trace-stack, untrace-stack):
+	New.
+
 2001-06-27  Marius Vollmer  <mvo@zagadka.ping.de>
 
 	* common-list.scm (member-if): Put in docstring for member-if, it
diff --git a/ice-9/debug.scm b/ice-9/debug.scm
index d2fe61324..0c25e5c70 100644
--- a/ice-9/debug.scm
+++ b/ice-9/debug.scm
@@ -109,8 +109,25 @@
 (define trace-level 0)
 (add-hook! abort-hook (lambda () (set! trace-level 0)))
 
+(define traced-stack-ids (list 'repl-stack))
+(define trace-all-stacks? #f)
+
+(define-public (trace-stack id)
+  "Add ID to the set of stack ids for which tracing is active.
+If `#t' is in this set, tracing is active regardless of stack context.
+To remove ID again, use `untrace-stack'.  If you add the same ID twice
+using `trace-stack', you will need to remove it twice."
+  (set! traced-stack-ids (cons id traced-stack-ids))
+  (set! trace-all-stacks? (memq #t traced-stack-ids)))
+
+(define-public (untrace-stack id)
+  "Remove ID from the set of stack ids for which tracing is active."
+  (set! traced-stack-ids (delq1! id traced-stack-ids))
+  (set! trace-all-stacks? (memq #t traced-stack-ids)))
+
 (define (trace-entry key cont tail)
-  (if (eq? (stack-id cont) 'repl-stack)
+  (if (or trace-all-stacks?
+	  (memq (stack-id cont) traced-stack-ids))
       (let ((cep (current-error-port))
 	    (frame (last-stack-frame cont)))
 	(if (not tail)
@@ -125,7 +142,8 @@
   )
 
 (define (trace-exit key cont retval)
-  (if (eq? (stack-id cont) 'repl-stack)
+  (if (or trace-all-stacks?
+	  (memq (stack-id cont) traced-stack-ids))
       (let ((cep (current-error-port)))
 	(set! trace-level (- trace-level 1))
 	(let indent ((n trace-level))