diff --git a/collects/macro-debugger/analysis/private/get-references.rkt b/collects/macro-debugger/analysis/private/get-references.rkt
index 544e945..48f6dae 100644
--- a/collects/macro-debugger/analysis/private/get-references.rkt
+++ b/collects/macro-debugger/analysis/private/get-references.rkt
@@ -123,8 +123,8 @@
        (void)]
       [(p:module z1 z2 rs ?1 locals tag rename check tag2 ?3 body shift)
        (recur locals check body)]
-      [(p:#%module-begin z1 z2 rs ?1 me body ?2)
-       (recur body)]
+      [(p:#%module-begin z1 z2 rs ?1 me body ?2 subs)
+       (recur body subs)]
       [(p:define-syntaxes z1 z2 rs ?1 prep rhs locals)
        (recur prep locals)
        (recur/phase-up rhs)]
@@ -164,6 +164,10 @@
        (recur inners)]
       [(p:require _ _ _ _ locals)
        (recur locals)]
+      [(p:submodule _ _ _ _ exp)
+       (recur exp)]
+      [(p:submodule* _ _ _ _)
+       (void)]
       [(p:#%stratified-body _ _ _ _ bderiv)
        (recur bderiv)]
       [(p:stop _ _ _ _) (void)]
diff --git a/collects/macro-debugger/model/deriv-c.rkt b/collects/macro-debugger/model/deriv-c.rkt
index 3c2fe10..43dcc83 100644
--- a/collects/macro-debugger/model/deriv-c.rkt
+++ b/collects/macro-debugger/model/deriv-c.rkt
@@ -56,7 +56,7 @@
 ;;   (make-p:#%module-begin <Base> Stx ModuleBegin/Phase ?exn)
 (define-struct (p:module prule) (prep tag rename check tag2 ?3 body shift)
   #:transparent)
-(define-struct (p:#%module-begin prule) (me body ?2) #:transparent)
+(define-struct (p:#%module-begin prule) (me body ?2 subs) #:transparent)
 
 ;;   (make-p:define-syntaxes <Base> (listof LocalAction) DerivLL (listof LocalAction))
 ;;   (make-p:define-values <Base> Deriv)
@@ -101,6 +101,9 @@
 ;;   (make-p:require <Base> (listof LocalAction))
 (define-struct (p:require prule) (locals) #:transparent)
 
+(define-struct (p:submodule prule) (exp) #:transparent)
+(define-struct (p:submodule* prule) () #:transparent)
+
 ;;   (make-p:#%stratified-body <Base> BDeriv)
 (define-struct (p:#%stratified-body prule) (bderiv) #:transparent)
 
diff --git a/collects/macro-debugger/model/deriv-parser.rkt b/collects/macro-debugger/model/deriv-parser.rkt
index 8b1325b..045f421 100644
--- a/collects/macro-debugger/model/deriv-parser.rkt
+++ b/collects/macro-debugger/model/deriv-parser.rkt
@@ -30,7 +30,7 @@
             (src-pos)
             (tokens basic-empty-tokens basic-tokens prim-tokens renames-tokens)
             (end EOF)
-            #|(debug "/tmp/ryan/DEBUG-PARSER.txt")|#
+            #| (debug "/tmp/DEBUG-PARSER.txt") |#
             (error deriv-error))
 
    ;; tokens
@@ -292,17 +292,23 @@
     ;;   instead appear directly here
     (Prim#%ModuleBegin
      (#:args e1 e2 rs)
-     [(prim-#%module-begin ! rename-one (? ModuleBegin/Phase) (? Eval))
+     [(prim-#%module-begin ! rename-one (? ModuleBegin/Phase) (? Eval) next (? ExpandSubmodules))
       (make p:#%module-begin e1 e2 rs $2 $3 $4
             (for/or ([la (in-list $5)])
-              (and (local-exn? la) (local-exn-exn la))))])
+              (and (local-exn? la) (local-exn-exn la)))
+            $7)])
     #|
     ;; restore this version when expander fixed
     (Prim#%ModuleBegin-REAL
      (#:args e1 e2 rs)
-     [(prim-#%module-begin ! rename-one (? ModuleBegin/Phase) !)
+     [(prim-#%module-begin ! rename-one (? ModuleBegin/Phase) ! (? ExpandSubmodules))
       (make p:#%module-begin e1 e2 rs $2 $3 $4 $5)])
     |#
+    (ExpandSubmodules
+     (#:skipped null)
+     [(enter-prim (? PrimModule) exit-prim (? ExpandSubmodules))
+      (cons ($2 $1 $3 null) $4)]
+     [() null])
 
     (ModuleBegin/Phase
      [((? ModulePass1) next-group (? ModulePass2) next-group (? ModulePass3))
@@ -336,6 +342,10 @@
       (make p:begin-for-syntax $1 $7 null $3 $4 $6 $7)]
      [(enter-prim prim-require (? Eval) exit-prim)
       (make p:require $1 $4 null #f $3)]
+     [(enter-prim prim-submodule ! (? ExpandSubmodules #|one|#) exit-prim)
+      (make p:submodule $1 $5 null $3 (car $4))]
+     [(enter-prim prim-submodule* ! exit-prim)
+      (make p:submodule* $1 $4 null $3)]
      [()
       (make p:stop e1 e1 null #f)])
 
diff --git a/collects/macro-debugger/model/deriv-tokens.rkt b/collects/macro-debugger/model/deriv-tokens.rkt
index 9591336..25edb6d 100644
--- a/collects/macro-debugger/model/deriv-tokens.rkt
+++ b/collects/macro-debugger/model/deriv-tokens.rkt
@@ -97,6 +97,7 @@
    prim-varref
    prim-#%stratified-body
    prim-begin-for-syntax
+   prim-submodule prim-submodule*
    ))
 
 ;; ** Signals to tokens
@@ -194,7 +195,10 @@
     (154 local-value-result      ,token-local-value-result)
     (155 prim-#%stratified-body)
     (156 prim-begin-for-syntax)
-    (157 prepare-env)))
+    (157 prepare-env)
+    (158 prim-submodule)
+    (159 prim-submodule*)
+    ))
 
 (define (signal->symbol sig)
   (if (symbol? sig)
diff --git a/collects/macro-debugger/model/reductions.rkt b/collects/macro-debugger/model/reductions.rkt
index 0f54430..6757bdf 100644
--- a/collects/macro-debugger/model/reductions.rkt
+++ b/collects/macro-debugger/model/reductions.rkt
@@ -97,13 +97,14 @@
         [Expr ?body body]
         [#:pattern ?form]
         [#:rename ?form shift])]
-    [(Wrap p:#%module-begin (e1 e2 rs ?1 me body ?2))
+    [(Wrap p:#%module-begin (e1 e2 rs ?1 me body ?2 subs))
      (R [! ?1]
         [#:pattern ?form]
         [#:rename ?form me]
         [#:pattern (?module-begin . ?forms)]
         [ModuleBegin/Phase ?forms body]
-        [! ?2])]
+        [! ?2]
+        [Submodules ?forms subs])]
     [(Wrap p:define-syntaxes (e1 e2 rs ?1 prep rhs locals))
      (R [! ?1]
         [#:pattern ?form]
@@ -252,6 +253,13 @@
         [#:pattern ?form]
         [#:walk e2 'macro])]
 
+    [(Wrap p:submodule* (e1 e2 rs ?1))
+     (R [! ?1])]
+    [(Wrap p:submodule (e1 e2 rs ?1 exp))
+     (R [! ?1]
+        [#:pattern ?form]
+        [Expr ?form exp])]
+
     [(Wrap p:stop (e1 e2 rs ?1))
      (R [! ?1])]
 
@@ -501,6 +509,18 @@
     [#f
      (R)]))
 
+(define (Submodules subs)
+  (match subs
+    ['()
+     (R)]
+    [(cons sub rest)
+     (R [#:pattern ?form]
+        [#:new-local-context
+         [#:pattern ?form]
+         [#:set-syntax (wderiv-e1 sub)]
+         [Expr ?form sub]]
+        [Submodules ?form rest])]))
+
 ;; List : ListDerivation -> RST
 (define (List ld)
   (match ld