diff --git a/compiler.rkt b/compiler.rkt
index c45ee1c..7b2966f 100644
--- a/compiler.rkt
+++ b/compiler.rkt
@@ -344,6 +344,9 @@
               ;; 2.  Next, evaluate the module body.
               (make-instruction-sequence 
                `(,(make-PerformStatement (make-ExtendEnvironment/Prefix! names))))
+
+              (make-AssignImmediateStatement (make-ModulePrefixTarget path)
+                                             (make-EnvWholePrefixReference 0))
               ;; TODO: we need to sequester the prefix of the module with the record.
               (compile (Module-code mod) 
                        (cons (Module-prefix mod) module-cenv)
@@ -2122,6 +2125,8 @@
     [(PrimitivesReference? target)
      target]
     [(ControlFrameTemporary? target)
+     target]
+    [(ModulePrefixTarget? target)
      target]))
 
 
diff --git a/il-structs.rkt b/il-structs.rkt
index 0ce9026..64809e4 100644
--- a/il-structs.rkt
+++ b/il-structs.rkt
@@ -45,7 +45,8 @@
                        EnvLexicalReference
                        EnvPrefixReference
                        PrimitivesReference                   
-                       ControlFrameTemporary))
+                       ControlFrameTemporary
+                       ModulePrefixTarget))
 
 
 ;; When we need to store a value temporarily in the top control frame, we can use this as a target.
@@ -57,6 +58,11 @@
   #:transparent)
 
 
+;; Targetting the prefix attribute of a module.
+(define-struct: ModulePrefixTarget ([path : ModuleLocator])
+  #:transparent)
+
+
 
 (define-struct: Label ([name : Symbol])
   #:transparent)
diff --git a/js-assembler/assemble-helpers.rkt b/js-assembler/assemble-helpers.rkt
index 58faf45..a121b90 100644
--- a/js-assembler/assemble-helpers.rkt
+++ b/js-assembler/assemble-helpers.rkt
@@ -82,7 +82,10 @@
     [(PrimitivesReference? target)
      (format "MACHINE.primitives[~s]" (symbol->string (PrimitivesReference-name target)))]
     [(ControlFrameTemporary? target)
-     (assemble-control-frame-temporary target)]))
+     (assemble-control-frame-temporary target)]
+    [(ModulePrefixTarget? target)
+     (format "MACHINE.modules[~s].prefix"
+             (symbol->string (ModuleLocator-name (ModulePrefixTarget-path target))))]))
 
 
 (: assemble-control-frame-temporary (ControlFrameTemporary -> String))
diff --git a/js-assembler/mini-runtime.js b/js-assembler/mini-runtime.js
index 5c4e64c..cbfd6e0 100644
--- a/js-assembler/mini-runtime.js
+++ b/js-assembler/mini-runtime.js
@@ -97,7 +97,7 @@
 	this.name = name;
 	this.label = label;
 	this.isInvoked = false;
-	this.exports = {};
+        this.prefix = false;
     };
 
 
diff --git a/simulator/simulator-structs.rkt b/simulator/simulator-structs.rkt
index 7f9baee..8a3b936 100644
--- a/simulator/simulator-structs.rkt
+++ b/simulator/simulator-structs.rkt
@@ -74,7 +74,8 @@
                                [self-path : Symbol]
                                [label : Symbol]
                                [invoked? : Boolean]
-                               [exports : (HashTable Symbol PrimitiveValue)])
+                               [exports : (HashTable Symbol PrimitiveValue)]
+                               [toplevel : (U False toplevel)])
   #:transparent
   #:mutable)
 
diff --git a/simulator/simulator.rkt b/simulator/simulator.rkt
index 8a842f4..f65617f 100644
--- a/simulator/simulator.rkt
+++ b/simulator/simulator.rkt
@@ -464,7 +464,8 @@
                                            (InstallModuleEntry!-path op))
                                           (InstallModuleEntry!-entry-point op)
                                           #f
-                                          (make-hash)))
+                                          (make-hash)
+                                          #f))
            'ok]
 
 
@@ -554,6 +555,15 @@
                 (hash-set! ht
                            (ControlFrameTemporary-name t)
                            (ensure-primitive-value v))
+                'ok))]
+    [(ModulePrefixTarget? t)
+     (lambda: ([m : machine] [v : SlotValue])
+              (let ([module-record
+                     (hash-ref (machine-modules m)
+                               (ModuleLocator-name
+                                (ModulePrefixTarget-path t)))])
+                (set-module-record-toplevel! module-record
+                                             (ensure-toplevel v))
                 'ok))]))