diff --git a/dlls/jscript/array.c b/dlls/jscript/array.c
index 03804bbdfca..60925552503 100644
--- a/dlls/jscript/array.c
+++ b/dlls/jscript/array.c
@@ -49,9 +49,14 @@ static const WCHAR unshiftW[] = {'u','n','s','h','i','f','t',0};
 
 static const WCHAR default_separatorW[] = {',',0};
 
+static inline ArrayInstance *array_from_jsdisp(jsdisp_t *jsdisp)
+{
+    return CONTAINING_RECORD(jsdisp, ArrayInstance, dispex);
+}
+
 static inline ArrayInstance *array_from_vdisp(vdisp_t *vdisp)
 {
-    return (ArrayInstance*)vdisp->u.jsdisp;
+    return array_from_jsdisp(vdisp->u.jsdisp);
 }
 
 static inline ArrayInstance *array_this(vdisp_t *jsthis)
@@ -113,13 +118,11 @@ static WCHAR *idx_to_str(DWORD idx, WCHAR *ptr)
     return ptr+1;
 }
 
-static HRESULT Array_get_length(script_ctx_t *ctx, vdisp_t *jsthis, jsval_t *r)
+static HRESULT Array_get_length(script_ctx_t *ctx, jsdisp_t *jsthis, jsval_t *r)
 {
-    ArrayInstance *This = array_from_vdisp(jsthis);
+    TRACE("%p\n", jsthis);
 
-    TRACE("%p %d\n", This, This->length);
-
-    *r = jsval_number(This->length);
+    *r = jsval_number(array_from_jsdisp(jsthis)->length);
     return S_OK;
 }
 
@@ -995,11 +998,13 @@ static HRESULT Array_unshift(script_ctx_t *ctx, vdisp_t *vthis, WORD flags, unsi
     return S_OK;
 }
 
-static HRESULT Array_get_value(script_ctx_t *ctx, vdisp_t *jsthis, jsval_t *r)
+static HRESULT Array_get_value(script_ctx_t *ctx, jsdisp_t *jsthis, jsval_t *r)
 {
+    ArrayInstance *array = array_from_jsdisp(jsthis);
+
     TRACE("\n");
 
-    return array_join(ctx, jsthis->u.jsdisp, array_from_vdisp(jsthis)->length, default_separatorW, r);
+    return array_join(ctx, &array->dispex, array->length, default_separatorW, r);
 }
 
 static void Array_destructor(jsdisp_t *dispex)
diff --git a/dlls/jscript/date.c b/dlls/jscript/date.c
index 6cd5a7521fa..5e5ef1c3c6d 100644
--- a/dlls/jscript/date.c
+++ b/dlls/jscript/date.c
@@ -94,9 +94,14 @@ static const WCHAR setYearW[] = {'s','e','t','Y','e','a','r',0};
 static const WCHAR UTCW[] = {'U','T','C',0};
 static const WCHAR parseW[] = {'p','a','r','s','e',0};
 
+static inline DateInstance *date_from_jsdisp(jsdisp_t *jsdisp)
+{
+    return CONTAINING_RECORD(jsdisp, DateInstance, dispex);
+}
+
 static inline DateInstance *date_this(vdisp_t *jsthis)
 {
-    return is_vclass(jsthis, JSCLASS_DATE) ? (DateInstance*)jsthis->u.jsdisp : NULL;
+    return is_vclass(jsthis, JSCLASS_DATE) ? date_from_jsdisp(jsthis->u.jsdisp) : NULL;
 }
 
 /*ECMA-262 3rd Edition    15.9.1.2 */
@@ -1917,11 +1922,11 @@ static HRESULT Date_setYear(script_ctx_t *ctx, vdisp_t *jsthis, WORD flags, unsi
     return S_OK;
 }
 
-static HRESULT Date_get_value(script_ctx_t *ctx, vdisp_t *jsthis, jsval_t *r)
+static HRESULT Date_get_value(script_ctx_t *ctx, jsdisp_t *jsthis, jsval_t *r)
 {
     TRACE("\n");
 
-    return dateobj_to_string((DateInstance*)jsthis->u.jsdisp, r);
+    return dateobj_to_string(date_from_jsdisp(jsthis), r);
 }
 
 static const builtin_prop_t Date_props[] = {
diff --git a/dlls/jscript/dispex.c b/dlls/jscript/dispex.c
index c3de526060b..6f225da3fb1 100644
--- a/dlls/jscript/dispex.c
+++ b/dlls/jscript/dispex.c
@@ -421,11 +421,7 @@ static HRESULT prop_get(jsdisp_t *This, dispex_prop_t *prop, DISPPARAMS *dp,
     switch(prop->type) {
     case PROP_BUILTIN:
         if(prop->u.p->getter) {
-            vdisp_t vthis;
-
-            set_jsdisp(&vthis, This);
-            hres = prop->u.p->getter(This->ctx, &vthis, r);
-            vdisp_release(&vthis);
+            hres = prop->u.p->getter(This->ctx, This, r);
         }else {
             jsdisp_t *obj;
 
diff --git a/dlls/jscript/function.c b/dlls/jscript/function.c
index 81a4c092c10..ec610cfd6b5 100644
--- a/dlls/jscript/function.c
+++ b/dlls/jscript/function.c
@@ -43,9 +43,14 @@ typedef struct {
     jsdisp_t *var_obj;
 } ArgumentsInstance;
 
+static inline FunctionInstance *function_from_jsdisp(jsdisp_t *jsdisp)
+{
+    return CONTAINING_RECORD(jsdisp, FunctionInstance, dispex);
+}
+
 static inline FunctionInstance *function_from_vdisp(vdisp_t *vdisp)
 {
-    return (FunctionInstance*)vdisp->u.jsdisp;
+    return function_from_jsdisp(vdisp->u.jsdisp);
 }
 
 static inline FunctionInstance *function_this(vdisp_t *jsthis)
@@ -362,13 +367,11 @@ HRESULT Function_invoke(jsdisp_t *func_this, IDispatch *jsthis, WORD flags, unsi
     return invoke_source(function->dispex.ctx, function, jsthis, argc, argv, r);
 }
 
-static HRESULT Function_get_length(script_ctx_t *ctx, vdisp_t *jsthis, jsval_t *r)
+static HRESULT Function_get_length(script_ctx_t *ctx, jsdisp_t *jsthis, jsval_t *r)
 {
-    FunctionInstance *This = function_from_vdisp(jsthis);
+    TRACE("%p\n", jsthis);
 
-    TRACE("%p %d\n", This, This->length);
-
-    *r = jsval_number(This->length);
+    *r = jsval_number(function_from_jsdisp(jsthis)->length);
     return S_OK;
 }
 
@@ -538,15 +541,14 @@ HRESULT Function_value(script_ctx_t *ctx, vdisp_t *jsthis, WORD flags, unsigned
     return invoke_value_proc(ctx, function, NULL, flags, argc, argv, r);
 }
 
-HRESULT Function_get_value(script_ctx_t *ctx, vdisp_t *jsthis, jsval_t *r)
+HRESULT Function_get_value(script_ctx_t *ctx, jsdisp_t *jsthis, jsval_t *r)
 {
-    FunctionInstance *function = (FunctionInstance*)jsthis->u.jsdisp;
     jsstr_t *str;
     HRESULT hres;
 
     TRACE("\n");
 
-    hres = function_to_string(function, &str);
+    hres = function_to_string(function_from_jsdisp(jsthis), &str);
     if(FAILED(hres))
         return hres;
 
@@ -554,9 +556,9 @@ HRESULT Function_get_value(script_ctx_t *ctx, vdisp_t *jsthis, jsval_t *r)
     return S_OK;
 }
 
-static HRESULT Function_get_arguments(script_ctx_t *ctx, vdisp_t *jsthis, jsval_t *r)
+static HRESULT Function_get_arguments(script_ctx_t *ctx, jsdisp_t *jsthis, jsval_t *r)
 {
-    FunctionInstance *function = (FunctionInstance*)jsthis->u.jsdisp;
+    FunctionInstance *function = function_from_jsdisp(jsthis);
 
     TRACE("\n");
 
diff --git a/dlls/jscript/jscript.h b/dlls/jscript/jscript.h
index 38baa074489..9dd772b1b4b 100644
--- a/dlls/jscript/jscript.h
+++ b/dlls/jscript/jscript.h
@@ -187,7 +187,7 @@ static inline jsdisp_t *get_jsdisp(vdisp_t *vdisp)
 }
 
 typedef HRESULT (*builtin_invoke_t)(script_ctx_t*,vdisp_t*,WORD,unsigned,jsval_t*,jsval_t*);
-typedef HRESULT (*builtin_getter_t)(script_ctx_t*,vdisp_t*,jsval_t*);
+typedef HRESULT (*builtin_getter_t)(script_ctx_t*,jsdisp_t*,jsval_t*);
 typedef HRESULT (*builtin_setter_t)(script_ctx_t*,vdisp_t*,jsval_t);
 
 HRESULT builtin_set_const(script_ctx_t*,vdisp_t*,jsval_t) DECLSPEC_HIDDEN;
@@ -296,7 +296,7 @@ HRESULT create_builtin_constructor(script_ctx_t*,builtin_invoke_t,const WCHAR*,c
 HRESULT Function_invoke(jsdisp_t*,IDispatch*,WORD,unsigned,jsval_t*,jsval_t*) DECLSPEC_HIDDEN;
 
 HRESULT Function_value(script_ctx_t*,vdisp_t*,WORD,unsigned,jsval_t*,jsval_t*) DECLSPEC_HIDDEN;
-HRESULT Function_get_value(script_ctx_t*,vdisp_t*,jsval_t*) DECLSPEC_HIDDEN;
+HRESULT Function_get_value(script_ctx_t*,jsdisp_t*,jsval_t*) DECLSPEC_HIDDEN;
 #define DEFAULT_FUNCTION_VALUE {NULL, Function_value,0, Function_get_value}
 
 HRESULT throw_eval_error(script_ctx_t*,HRESULT,const WCHAR*) DECLSPEC_HIDDEN;
diff --git a/dlls/jscript/jsregexp.c b/dlls/jscript/jsregexp.c
index 4bec773d00f..ed3d0b1728a 100644
--- a/dlls/jscript/jsregexp.c
+++ b/dlls/jscript/jsregexp.c
@@ -58,9 +58,14 @@ static const WCHAR idx7W[] = {'$','7',0};
 static const WCHAR idx8W[] = {'$','8',0};
 static const WCHAR idx9W[] = {'$','9',0};
 
+static inline RegExpInstance *regexp_from_jsdisp(jsdisp_t *jsdisp)
+{
+    return CONTAINING_RECORD(jsdisp, RegExpInstance, dispex);
+}
+
 static inline RegExpInstance *regexp_from_vdisp(vdisp_t *vdisp)
 {
-    return (RegExpInstance*)vdisp->u.jsdisp;
+    return regexp_from_jsdisp(vdisp->u.jsdisp);
 }
 
 static void set_last_index(RegExpInstance *This, DWORD last_index)
@@ -243,13 +248,11 @@ static HRESULT regexp_match(script_ctx_t *ctx, jsdisp_t *dispex, jsstr_t *jsstr,
     return S_OK;
 }
 
-static HRESULT RegExp_get_source(script_ctx_t *ctx, vdisp_t *jsthis, jsval_t *r)
+static HRESULT RegExp_get_source(script_ctx_t *ctx, jsdisp_t *jsthis, jsval_t *r)
 {
-    RegExpInstance *This = regexp_from_vdisp(jsthis);
-
     TRACE("\n");
 
-    *r = jsval_string(jsstr_addref(This->str));
+    *r = jsval_string(jsstr_addref(regexp_from_jsdisp(jsthis)->str));
     return S_OK;
 }
 
@@ -259,7 +262,7 @@ static HRESULT RegExp_set_source(script_ctx_t *ctx, vdisp_t *jsthis, jsval_t val
     return E_NOTIMPL;
 }
 
-static HRESULT RegExp_get_global(script_ctx_t *ctx, vdisp_t *jsthis, jsval_t *r)
+static HRESULT RegExp_get_global(script_ctx_t *ctx, jsdisp_t *jsthis, jsval_t *r)
 {
     FIXME("\n");
     return E_NOTIMPL;
@@ -271,7 +274,7 @@ static HRESULT RegExp_set_global(script_ctx_t *ctx, vdisp_t *jsthis, jsval_t val
     return E_NOTIMPL;
 }
 
-static HRESULT RegExp_get_ignoreCase(script_ctx_t *ctx, vdisp_t *jsthis, jsval_t *r)
+static HRESULT RegExp_get_ignoreCase(script_ctx_t *ctx, jsdisp_t *jsthis, jsval_t *r)
 {
     FIXME("\n");
     return E_NOTIMPL;
@@ -283,7 +286,7 @@ static HRESULT RegExp_set_ignoreCase(script_ctx_t *ctx, vdisp_t *jsthis, jsval_t
     return E_NOTIMPL;
 }
 
-static HRESULT RegExp_get_multiline(script_ctx_t *ctx, vdisp_t *jsthis, jsval_t *r)
+static HRESULT RegExp_get_multiline(script_ctx_t *ctx, jsdisp_t *jsthis, jsval_t *r)
 {
     FIXME("\n");
     return E_NOTIMPL;
@@ -310,9 +313,9 @@ static INT index_from_val(script_ctx_t *ctx, jsval_t v)
     return is_int32(n) ? n : 0;
 }
 
-static HRESULT RegExp_get_lastIndex(script_ctx_t *ctx, vdisp_t *jsthis, jsval_t *r)
+static HRESULT RegExp_get_lastIndex(script_ctx_t *ctx, jsdisp_t *jsthis, jsval_t *r)
 {
-    RegExpInstance *regexp = regexp_from_vdisp(jsthis);
+    RegExpInstance *regexp = regexp_from_jsdisp(jsthis);
 
     TRACE("\n");
 
@@ -854,61 +857,61 @@ static HRESULT global_idx(script_ctx_t *ctx, DWORD idx, jsval_t *r)
     return S_OK;
 }
 
-static HRESULT RegExpConstr_get_idx1(script_ctx_t *ctx, vdisp_t *jsthis, jsval_t *r)
+static HRESULT RegExpConstr_get_idx1(script_ctx_t *ctx, jsdisp_t *jsthis, jsval_t *r)
 {
     TRACE("\n");
     return global_idx(ctx, 0, r);
 }
 
-static HRESULT RegExpConstr_get_idx2(script_ctx_t *ctx, vdisp_t *jsthis, jsval_t *r)
+static HRESULT RegExpConstr_get_idx2(script_ctx_t *ctx, jsdisp_t *jsthis, jsval_t *r)
 {
     TRACE("\n");
     return global_idx(ctx, 1, r);
 }
 
-static HRESULT RegExpConstr_get_idx3(script_ctx_t *ctx, vdisp_t *jsthis, jsval_t *r)
+static HRESULT RegExpConstr_get_idx3(script_ctx_t *ctx, jsdisp_t *jsthis, jsval_t *r)
 {
     TRACE("\n");
     return global_idx(ctx, 2, r);
 }
 
-static HRESULT RegExpConstr_get_idx4(script_ctx_t *ctx, vdisp_t *jsthis, jsval_t *r)
+static HRESULT RegExpConstr_get_idx4(script_ctx_t *ctx, jsdisp_t *jsthis, jsval_t *r)
 {
     TRACE("\n");
     return global_idx(ctx, 3, r);
 }
 
-static HRESULT RegExpConstr_get_idx5(script_ctx_t *ctx, vdisp_t *jsthis, jsval_t *r)
+static HRESULT RegExpConstr_get_idx5(script_ctx_t *ctx, jsdisp_t *jsthis, jsval_t *r)
 {
     TRACE("\n");
     return global_idx(ctx, 4, r);
 }
 
-static HRESULT RegExpConstr_get_idx6(script_ctx_t *ctx, vdisp_t *jsthis, jsval_t *r)
+static HRESULT RegExpConstr_get_idx6(script_ctx_t *ctx, jsdisp_t *jsthis, jsval_t *r)
 {
     TRACE("\n");
     return global_idx(ctx, 5, r);
 }
 
-static HRESULT RegExpConstr_get_idx7(script_ctx_t *ctx, vdisp_t *jsthis, jsval_t *r)
+static HRESULT RegExpConstr_get_idx7(script_ctx_t *ctx, jsdisp_t *jsthis, jsval_t *r)
 {
     TRACE("\n");
     return global_idx(ctx, 6, r);
 }
 
-static HRESULT RegExpConstr_get_idx8(script_ctx_t *ctx, vdisp_t *jsthis, jsval_t *r)
+static HRESULT RegExpConstr_get_idx8(script_ctx_t *ctx, jsdisp_t *jsthis, jsval_t *r)
 {
     TRACE("\n");
     return global_idx(ctx, 7, r);
 }
 
-static HRESULT RegExpConstr_get_idx9(script_ctx_t *ctx, vdisp_t *jsthis, jsval_t *r)
+static HRESULT RegExpConstr_get_idx9(script_ctx_t *ctx, jsdisp_t *jsthis, jsval_t *r)
 {
     TRACE("\n");
     return global_idx(ctx, 8, r);
 }
 
-static HRESULT RegExpConstr_get_leftContext(script_ctx_t *ctx, vdisp_t *jsthis, jsval_t *r)
+static HRESULT RegExpConstr_get_leftContext(script_ctx_t *ctx, jsdisp_t *jsthis, jsval_t *r)
 {
     jsstr_t *ret;
 
@@ -922,7 +925,7 @@ static HRESULT RegExpConstr_get_leftContext(script_ctx_t *ctx, vdisp_t *jsthis,
     return S_OK;
 }
 
-static HRESULT RegExpConstr_get_rightContext(script_ctx_t *ctx, vdisp_t *jsthis, jsval_t *r)
+static HRESULT RegExpConstr_get_rightContext(script_ctx_t *ctx, jsdisp_t *jsthis, jsval_t *r)
 {
     jsstr_t *ret;
 
diff --git a/dlls/jscript/number.c b/dlls/jscript/number.c
index 4338addaaea..0a648d05310 100644
--- a/dlls/jscript/number.c
+++ b/dlls/jscript/number.c
@@ -44,9 +44,14 @@ static const WCHAR valueOfW[] = {'v','a','l','u','e','O','f',0};
 #define NUMBER_TOSTRING_BUF_SIZE 64
 #define NUMBER_DTOA_SIZE 18
 
+static inline NumberInstance *number_from_jsdisp(jsdisp_t *jsdisp)
+{
+    return CONTAINING_RECORD(jsdisp, NumberInstance, dispex);
+}
+
 static inline NumberInstance *number_from_vdisp(vdisp_t *vdisp)
 {
-    return (NumberInstance*)vdisp->u.jsdisp;
+    return number_from_jsdisp(vdisp->u.jsdisp);
 }
 
 static inline NumberInstance *number_this(vdisp_t *jsthis)
@@ -500,9 +505,9 @@ static HRESULT Number_valueOf(script_ctx_t *ctx, vdisp_t *jsthis, WORD flags, un
     return S_OK;
 }
 
-static HRESULT Number_get_value(script_ctx_t *ctx, vdisp_t *jsthis, jsval_t *r)
+static HRESULT Number_get_value(script_ctx_t *ctx, jsdisp_t *jsthis, jsval_t *r)
 {
-    NumberInstance *number = number_from_vdisp(jsthis);
+    NumberInstance *number = number_from_jsdisp(jsthis);
 
     TRACE("(%p)\n", number);
 
diff --git a/dlls/jscript/object.c b/dlls/jscript/object.c
index e19611438cd..ffb7ff8ceb5 100644
--- a/dlls/jscript/object.c
+++ b/dlls/jscript/object.c
@@ -207,7 +207,7 @@ static HRESULT Object_isPrototypeOf(script_ctx_t *ctx, vdisp_t *jsthis, WORD fla
     return E_NOTIMPL;
 }
 
-static HRESULT Object_get_value(script_ctx_t *ctx, vdisp_t *jsthis, jsval_t *r)
+static HRESULT Object_get_value(script_ctx_t *ctx, jsdisp_t *jsthis, jsval_t *r)
 {
     jsstr_t *ret;
 
diff --git a/dlls/jscript/string.c b/dlls/jscript/string.c
index 4276f92cfaa..3f8367589c5 100644
--- a/dlls/jscript/string.c
+++ b/dlls/jscript/string.c
@@ -68,9 +68,14 @@ static const WCHAR toLocaleUpperCaseW[] = {'t','o','L','o','c','a','l','e','U','
 static const WCHAR localeCompareW[] = {'l','o','c','a','l','e','C','o','m','p','a','r','e',0};
 static const WCHAR fromCharCodeW[] = {'f','r','o','m','C','h','a','r','C','o','d','e',0};
 
+static inline StringInstance *string_from_jsdisp(jsdisp_t *jsdisp)
+{
+    return CONTAINING_RECORD(jsdisp, StringInstance, dispex);
+}
+
 static inline StringInstance *string_from_vdisp(vdisp_t *vdisp)
 {
-    return (StringInstance*)vdisp->u.jsdisp;
+    return string_from_jsdisp(vdisp->u.jsdisp);
 }
 
 static inline StringInstance *string_this(vdisp_t *jsthis)
@@ -106,9 +111,9 @@ static HRESULT get_string_flat_val(script_ctx_t *ctx, vdisp_t *jsthis, jsstr_t *
     return E_OUTOFMEMORY;
 }
 
-static HRESULT String_get_length(script_ctx_t *ctx, vdisp_t *jsthis, jsval_t *r)
+static HRESULT String_get_length(script_ctx_t *ctx, jsdisp_t *jsthis, jsval_t *r)
 {
-    StringInstance *string = string_from_vdisp(jsthis);
+    StringInstance *string = (StringInstance*)jsthis;
 
     TRACE("%p\n", jsthis);
 
@@ -1467,9 +1472,9 @@ static HRESULT String_localeCompare(script_ctx_t *ctx, vdisp_t *jsthis, WORD fla
     return E_NOTIMPL;
 }
 
-static HRESULT String_get_value(script_ctx_t *ctx, vdisp_t *jsthis, jsval_t *r)
+static HRESULT String_get_value(script_ctx_t *ctx, jsdisp_t *jsthis, jsval_t *r)
 {
-    StringInstance *This = string_from_vdisp(jsthis);
+    StringInstance *This = (StringInstance*)jsthis;
 
     TRACE("\n");