diff --git a/collects/scheme/package.ss b/collects/scheme/package.ss
index 21fd108310..7cb872030d 100644
--- a/collects/scheme/package.ss
+++ b/collects/scheme/package.ss
@@ -291,7 +291,7 @@
                         (let ([star? (free-identifier=? #'def #'define*-syntaxes)]
                               [ids (syntax->list #'(id ...))])
                           (let* ([def-ctx (if star?
-                                              (syntax-local-make-definition-context)
+                                              (syntax-local-make-definition-context (car def-ctxes))
                                               (car def-ctxes))]
                                  [ids (if star? 
                                           (map (add-package-context (list def-ctx)) ids)
diff --git a/collects/scribblings/reference/stx-trans.scrbl b/collects/scribblings/reference/stx-trans.scrbl
index 50e2613777..fac8180a96 100644
--- a/collects/scribblings/reference/stx-trans.scrbl
+++ b/collects/scribblings/reference/stx-trans.scrbl
@@ -198,7 +198,9 @@ Returns @scheme[#t] if @scheme[v] is an @tech{internal-definition
 context}, @scheme[#f] otherwise.}
 
 
-@defproc[(syntax-local-make-definition-context) internal-definition-context?]{
+@defproc[(syntax-local-make-definition-context
+          [intdef-ctx (or/c internal-definition-context? #f) #f])
+         internal-definition-context?]{
 
 Creates an opaque @tech{internal-definition context} value to be used
 with @scheme[local-expand] and other functions. A transformer should
@@ -212,6 +214,11 @@ Finally, the transformer must call
 added; if an unsealed @tech{internal-definition context} is detected
 in a fully expanded expression, the @exnraise[exn:fail:contract].
 
+If @scheme[intdef-ctx] is not @scheme[#f], then the new
+internal-definition context extends the given one. That is, expanding
+in the new internal-definition context can use bindings previously
+introduced into @scheme[intdef-ctx].
+
 @transform-time[]}
 
 
diff --git a/src/mzscheme/src/env.c b/src/mzscheme/src/env.c
index 66c1f595df..b3e1720277 100644
--- a/src/mzscheme/src/env.c
+++ b/src/mzscheme/src/env.c
@@ -525,7 +525,7 @@ static void make_kernel_env(void)
   GLOBAL_PRIM_W_ARITY("syntax-local-name", local_exp_time_name, 0, 0, env);
   GLOBAL_PRIM_W_ARITY("syntax-local-context", local_context, 0, 0, env);
   GLOBAL_PRIM_W_ARITY("syntax-local-phase-level", local_phase_level, 0, 0, env);
-  GLOBAL_PRIM_W_ARITY("syntax-local-make-definition-context", local_make_intdef_context, 0, 0, env);
+  GLOBAL_PRIM_W_ARITY("syntax-local-make-definition-context", local_make_intdef_context, 0, 1, env);
   GLOBAL_PRIM_W_ARITY("internal-definition-context-seal", intdef_context_seal, 1, 1, env);
   GLOBAL_PRIM_W_ARITY("internal-definition-context?", intdef_context_p, 1, 1, env);
   GLOBAL_PRIM_W_ARITY("identifier-remove-from-definition-context", id_intdef_remove, 2, 2, env);
@@ -4305,13 +4305,24 @@ local_phase_level(int argc, Scheme_Object *argv[])
 static Scheme_Object *
 local_make_intdef_context(int argc, Scheme_Object *argv[])
 {
-  Scheme_Comp_Env *env;
+  Scheme_Comp_Env *env, *senv;
   Scheme_Object *c, *rib;
 
   env = scheme_current_thread->current_local_env;
   if (!env)
     scheme_raise_exn(MZEXN_FAIL_CONTRACT, "syntax-local-make-definition-context: not currently transforming");
   
+  if (argc && SCHEME_TRUEP(argv[0])) {
+    if (!SAME_TYPE(scheme_intdef_context_type, SCHEME_TYPE(argv[0])))
+      scheme_wrong_type("syntax-local-bind-syntaxes", "internal-definition context or #f", 0, argc, argv);
+    senv = (Scheme_Comp_Env *)SCHEME_PTR1_VAL(argv[0]);
+    if (!scheme_is_sub_env(senv, env)) {
+      scheme_raise_exn(MZEXN_FAIL_CONTRACT, "syntax-local-make-definition-context: transforming context does "
+                       "not match given internal-definition context");
+    }
+    env = senv;
+  }
+
   rib = scheme_make_rename_rib();
 
   c = scheme_alloc_object();