diff --git a/dlls/jscript/dispex.c b/dlls/jscript/dispex.c
index 4eda70470e5..640e954d97b 100644
--- a/dlls/jscript/dispex.c
+++ b/dlls/jscript/dispex.c
@@ -39,7 +39,8 @@ typedef enum {
     PROP_JSVAL,
     PROP_BUILTIN,
     PROP_PROTREF,
-    PROP_DELETED
+    PROP_DELETED,
+    PROP_IDX
 } prop_type_t;
 
 struct _dispex_prop_t {
@@ -52,6 +53,7 @@ struct _dispex_prop_t {
         jsval_t val;
         const builtin_prop_t *p;
         DWORD ref;
+        unsigned idx;
     } u;
 
     int bucket_head;
@@ -219,6 +221,23 @@ static HRESULT find_prop_name(jsdisp_t *This, unsigned hash, const WCHAR *name,
         return S_OK;
     }
 
+    if(This->builtin_info->idx_length) {
+        const WCHAR *ptr;
+        unsigned idx = 0;
+
+        for(ptr = name; isdigitW(*ptr) && idx < 0x10000; ptr++)
+            idx = idx*10 + (*ptr-'0');
+        if(!*ptr && idx < This->builtin_info->idx_length(This)) {
+            prop = alloc_prop(This, name, PROP_IDX, This->builtin_info->idx_put ? 0 : PROPF_CONST);
+            if(!prop)
+                return E_OUTOFMEMORY;
+
+            prop->u.idx = idx;
+            *ret = prop;
+            return S_OK;
+        }
+    }
+
     *ret = NULL;
     return S_OK;
 }
@@ -383,10 +402,14 @@ static HRESULT invoke_prop_func(jsdisp_t *This, IDispatch *jsthis, dispex_prop_t
 
         return disp_call_value(This->ctx, get_object(prop->u.val), jsthis, flags, argc, argv, r);
     }
-    default:
-        ERR("type %d\n", prop->type);
+    case PROP_IDX:
+        FIXME("Invoking PROP_IDX not yet supported\n");
+        return E_NOTIMPL;
+    case PROP_DELETED:
+        assert(0);
     }
 
+    assert(0);
     return E_FAIL;
 }
 
@@ -423,6 +446,9 @@ static HRESULT prop_get(jsdisp_t *This, dispex_prop_t *prop, DISPPARAMS *dp,
     case PROP_JSVAL:
         hres = jsval_copy(prop->u.val, r);
         break;
+    case PROP_IDX:
+        hres = This->builtin_info->idx_get(This, prop->u.idx, r);
+        break;
     default:
         ERR("type %d\n", prop->type);
         return E_FAIL;
@@ -463,6 +489,8 @@ static HRESULT prop_put(jsdisp_t *This, dispex_prop_t *prop, jsval_t val, IServi
     case PROP_JSVAL:
         jsval_release(prop->u.val);
         break;
+    case PROP_IDX:
+        return This->builtin_info->idx_put(This, prop->u.idx, val);
     default:
         ERR("type %d\n", prop->type);
         return E_FAIL;
@@ -479,7 +507,6 @@ static HRESULT prop_put(jsdisp_t *This, dispex_prop_t *prop, jsval_t val, IServi
     if(This->builtin_info->on_put)
         This->builtin_info->on_put(This, prop->name);
 
-    TRACE("%s = %s\n", debugstr_w(prop->name), debugstr_jsval(val));
     return S_OK;
 }
 
diff --git a/dlls/jscript/function.c b/dlls/jscript/function.c
index 299fafba515..329bec2aef0 100644
--- a/dlls/jscript/function.c
+++ b/dlls/jscript/function.c
@@ -37,6 +37,12 @@ typedef struct {
     jsdisp_t *arguments;
 } FunctionInstance;
 
+typedef struct {
+    jsdisp_t jsdisp;
+    FunctionInstance *function;
+    jsdisp_t *var_obj;
+} ArgumentsInstance;
+
 static inline FunctionInstance *function_from_vdisp(vdisp_t *vdisp)
 {
     return (FunctionInstance*)vdisp->u.jsdisp;
@@ -77,61 +83,102 @@ static HRESULT Arguments_value(script_ctx_t *ctx, vdisp_t *jsthis, WORD flags, u
     return E_NOTIMPL;
 }
 
+static void Arguments_destructor(jsdisp_t *jsdisp)
+{
+    ArgumentsInstance *arguments = (ArgumentsInstance*)jsdisp;
+
+    jsdisp_release(&arguments->function->dispex);
+    jsdisp_release(arguments->var_obj);
+    heap_free(arguments);
+}
+
+static unsigned Arguments_idx_length(jsdisp_t *jsdisp)
+{
+    ArgumentsInstance *arguments = (ArgumentsInstance*)jsdisp;
+    return arguments->function->length;
+}
+
+static HRESULT Arguments_idx_get(jsdisp_t *jsdisp, unsigned idx, jsval_t *res)
+{
+    ArgumentsInstance *arguments = (ArgumentsInstance*)jsdisp;
+
+    TRACE("%p[%u]\n", arguments, idx);
+
+    /* FIXME: Accessing by name won't work for duplicated argument names */
+    return jsdisp_propget_name(arguments->var_obj, arguments->function->func_code->params[idx], res);
+}
+
+static HRESULT Arguments_idx_put(jsdisp_t *jsdisp, unsigned idx, jsval_t val)
+{
+    ArgumentsInstance *arguments = (ArgumentsInstance*)jsdisp;
+
+    TRACE("%p[%u] = %s\n", arguments, idx, debugstr_jsval(val));
+
+    /* FIXME: Accessing by name won't work for duplicated argument names */
+    return jsdisp_propput_name(arguments->var_obj, arguments->function->func_code->params[idx], val);
+}
+
 static const builtin_info_t Arguments_info = {
     JSCLASS_ARGUMENTS,
     {NULL, Arguments_value, 0},
     0, NULL,
+    Arguments_destructor,
     NULL,
-    NULL
+    Arguments_idx_length,
+    Arguments_idx_get,
+    Arguments_idx_put
 };
 
-static HRESULT create_arguments(script_ctx_t *ctx, IDispatch *calee, unsigned argc, jsval_t *argv, jsdisp_t **ret)
+static HRESULT create_arguments(script_ctx_t *ctx, FunctionInstance *calee, jsdisp_t *var_obj,
+        unsigned argc, jsval_t *argv, jsdisp_t **ret)
 {
-    jsdisp_t *args;
-    DWORD i;
+    ArgumentsInstance *args;
+    unsigned i;
     HRESULT hres;
 
     static const WCHAR caleeW[] = {'c','a','l','l','e','e',0};
 
-    args = heap_alloc_zero(sizeof(jsdisp_t));
+    args = heap_alloc_zero(sizeof(*args));
     if(!args)
         return E_OUTOFMEMORY;
 
-    hres = init_dispex_from_constr(args, ctx, &Arguments_info, ctx->object_constr);
+    hres = init_dispex_from_constr(&args->jsdisp, ctx, &Arguments_info, ctx->object_constr);
     if(FAILED(hres)) {
         heap_free(args);
         return hres;
     }
 
-    for(i=0; i < argc; i++) {
+    jsdisp_addref(&calee->dispex);
+    args->function = calee;
+    args->var_obj = jsdisp_addref(var_obj);
+
+    /* Store unnamed arguments directly in arguments object */
+    for(i = calee->length; i < argc; i++) {
         WCHAR buf[12];
 
         static const WCHAR formatW[] = {'%','d',0};
 
         sprintfW(buf, formatW, i);
-        hres = jsdisp_propput_dontenum(args, buf, argv[i]);
+        hres = jsdisp_propput_dontenum(&args->jsdisp, buf, argv[i]);
         if(FAILED(hres))
             break;
     }
 
     if(SUCCEEDED(hres)) {
-        hres = jsdisp_propput_dontenum(args, lengthW, jsval_number(argc));
-
+        hres = jsdisp_propput_dontenum(&args->jsdisp, lengthW, jsval_number(argc));
         if(SUCCEEDED(hres))
-            hres = jsdisp_propput_dontenum(args, caleeW, jsval_disp(calee));
+            hres = jsdisp_propput_dontenum(&args->jsdisp, caleeW, jsval_disp(to_disp(&calee->dispex)));
     }
-
     if(FAILED(hres)) {
-        jsdisp_release(args);
+        jsdisp_release(&args->jsdisp);
         return hres;
     }
 
-    *ret = args;
+    *ret = &args->jsdisp;
     return S_OK;
 }
 
-static HRESULT create_var_disp(script_ctx_t *ctx, FunctionInstance *function, jsdisp_t *arg_disp,
-        unsigned argc, jsval_t *argv, jsdisp_t **ret)
+static HRESULT create_var_disp(script_ctx_t *ctx, FunctionInstance *function, unsigned argc, jsval_t *argv, jsdisp_t **ret)
 {
     jsdisp_t *var_disp;
     HRESULT hres;
@@ -140,9 +187,7 @@ static HRESULT create_var_disp(script_ctx_t *ctx, FunctionInstance *function, js
     if(FAILED(hres))
         return hres;
 
-    hres = jsdisp_propput_name(var_disp, argumentsW, jsval_obj(arg_disp));
-    if(SUCCEEDED(hres))
-        hres = init_parameters(var_disp, function, argc, argv);
+    hres = init_parameters(var_disp, function, argc, argv);
     if(FAILED(hres)) {
         jsdisp_release(var_disp);
         return hres;
@@ -165,20 +210,23 @@ static HRESULT invoke_source(script_ctx_t *ctx, FunctionInstance *function, IDis
         return E_FAIL;
     }
 
-    hres = create_arguments(ctx, to_disp(&function->dispex), argc, argv, &arg_disp);
+    hres = create_var_disp(ctx, function, argc, argv, &var_disp);
     if(FAILED(hres))
         return hres;
 
-    hres = create_var_disp(ctx, function, arg_disp, argc, argv, &var_disp);
+    hres = create_arguments(ctx, function, var_disp, argc, argv, &arg_disp);
     if(FAILED(hres)) {
-        jsdisp_release(arg_disp);
+        jsdisp_release(var_disp);
         return hres;
     }
 
-    hres = scope_push(function->scope_chain, var_disp, to_disp(var_disp), &scope);
+    hres = jsdisp_propput_name(var_disp, argumentsW, jsval_obj(arg_disp));
     if(SUCCEEDED(hres)) {
-        hres = create_exec_ctx(ctx, this_obj, var_disp, scope, FALSE, &exec_ctx);
-        scope_release(scope);
+        hres = scope_push(function->scope_chain, var_disp, to_disp(var_disp), &scope);
+        if(SUCCEEDED(hres)) {
+            hres = create_exec_ctx(ctx, this_obj, var_disp, scope, FALSE, &exec_ctx);
+            scope_release(scope);
+        }
     }
     jsdisp_release(var_disp);
     if(SUCCEEDED(hres)) {
diff --git a/dlls/jscript/jscript.h b/dlls/jscript/jscript.h
index 0ab2e065038..1c848236ed7 100644
--- a/dlls/jscript/jscript.h
+++ b/dlls/jscript/jscript.h
@@ -200,6 +200,9 @@ typedef struct {
     const builtin_prop_t *props;
     void (*destructor)(jsdisp_t*);
     void (*on_put)(jsdisp_t*,const WCHAR*);
+    unsigned (*idx_length)(jsdisp_t*);
+    HRESULT (*idx_get)(jsdisp_t*,unsigned,jsval_t*);
+    HRESULT (*idx_put)(jsdisp_t*,unsigned,jsval_t);
 } builtin_info_t;
 
 struct jsdisp_t {
diff --git a/dlls/jscript/tests/lang.js b/dlls/jscript/tests/lang.js
index 4f5f29c7455..fa3d6d2aca7 100644
--- a/dlls/jscript/tests/lang.js
+++ b/dlls/jscript/tests/lang.js
@@ -74,6 +74,15 @@ function testFunc1(x, y) {
     ok(arguments.callee === testFunc1, "arguments.calee !== testFunc1");
     ok(testFunc1.arguments === arguments, "testFunc1.arguments = " + testFunc1.arguments);
 
+    x = false;
+    ok(arguments[0] === false, "arguments[0] is not false");
+    arguments[1] = "x";
+    ok(y === "x", "y = " + y);
+    ok(arguments[1] === "x", "arguments[1] = " + arguments[1]);
+
+    ok(arguments["0x0"] === undefined, "arguments['0x0'] = " + arguments["0x0"]);
+    ok(arguments["x"] === undefined, "arguments['x'] = " + arguments["x"]);
+
     ok(this === test, "this !== test");
     eval('ok(this === test, "this !== test");');