diff --git a/dlls/msvcrt/tests/cpp.c b/dlls/msvcrt/tests/cpp.c
index 140d8b2224c..8baf9b66d0e 100644
--- a/dlls/msvcrt/tests/cpp.c
+++ b/dlls/msvcrt/tests/cpp.c
@@ -840,13 +840,13 @@ static inline void/*rtti_object_locator*/ *get_obj_locator( void *cppobj )
 }
 
 #ifndef __x86_64__
-#define RTTI_SIGNATURE 0
 #define DEFINE_RTTI_REF(type, name) type *name
 #define RTTI_REF(instance, name) &instance.name
+#define RTTI_REF_SIG0(instance, name, base) RTTI_REF(instance, name)
 #else
-#define RTTI_SIGNATURE 1
 #define DEFINE_RTTI_REF(type, name) unsigned name
 #define RTTI_REF(instance, name) FIELD_OFFSET(struct rtti_data, name)
+#define RTTI_REF_SIG0(instance, name, base) ((char*)&instance.name-base)
 #endif
 /* Test RTTI functions */
 static void test_rtti(void)
@@ -894,24 +894,33 @@ static void test_rtti(void)
     { {RTTI_REF(simple_class_rtti, type_info[0]), 0, {0, 0, 0}, 0} },
     { {RTTI_REF(simple_class_rtti, base_descriptor[0])} },
     {0, 0, 1, RTTI_REF(simple_class_rtti, base_array)},
-    {RTTI_SIGNATURE, 0, 0, RTTI_REF(simple_class_rtti, type_info[0]), RTTI_REF(simple_class_rtti, object_hierarchy), RTTI_REF(simple_class_rtti, object_locator)}
+    {1, 0, 0, RTTI_REF(simple_class_rtti, type_info[0]), RTTI_REF(simple_class_rtti, object_hierarchy), RTTI_REF(simple_class_rtti, object_locator)}
   }, child_class_rtti = {
     { {NULL, NULL, "simple_class"}, {NULL, NULL, "child_class"} },
     { {RTTI_REF(child_class_rtti, type_info[1]), 0, {4, -1, 0}, 0}, {RTTI_REF(child_class_rtti, type_info[0]), 0, {8, -1, 0}, 0} },
     { {RTTI_REF(child_class_rtti, base_descriptor[0]), RTTI_REF(child_class_rtti, base_descriptor[1])} },
     {0, 0, 2, RTTI_REF(child_class_rtti, base_array)},
-    {RTTI_SIGNATURE, 0, 0, RTTI_REF(child_class_rtti, type_info[1]), RTTI_REF(child_class_rtti, object_hierarchy), RTTI_REF(child_class_rtti, object_locator)}
+    {1, 0, 0, RTTI_REF(child_class_rtti, type_info[1]), RTTI_REF(child_class_rtti, object_hierarchy), RTTI_REF(child_class_rtti, object_locator)}
   };
+  static struct rtti_data simple_class_sig0_rtti, child_class_sig0_rtti;
+
   void *simple_class_vtbl[2] = {&simple_class_rtti.object_locator};
   void *simple_class = &simple_class_vtbl[1];
   void *child_class_vtbl[2] = {&child_class_rtti.object_locator};
   void *child_class = &child_class_vtbl[1];
+  void *simple_class_sig0_vtbl[2] = {&simple_class_sig0_rtti.object_locator};
+  void *simple_class_sig0 = &simple_class_sig0_vtbl[1];
+  void *child_class_sig0_vtbl[2] = {&child_class_sig0_rtti.object_locator};
+  void *child_class_sig0 = &child_class_sig0_vtbl[1];
 
   static const char* e_name = "name";
   type_info *ti,*bti;
   exception e,b;
   void *casted;
   BOOL old_signature;
+#ifdef __x86_64__
+  char *base = (char*)GetModuleHandleW(NULL);
+#endif
 
   if (bAncientVersion ||
       !p__RTCastToVoid || !p__RTtypeid || !pexception_ctor || !pbad_typeid_ctor
@@ -922,7 +931,7 @@ static void test_rtti(void)
   call_func2(pbad_typeid_ctor, &b, e_name);
 
   obj_locator = get_obj_locator(&e);
-  if(obj_locator->signature!=RTTI_SIGNATURE && sizeof(void*)>sizeof(int))
+  if(obj_locator->signature!=1 && sizeof(void*)>sizeof(int))
     old_signature = TRUE;
   else
     old_signature = FALSE;
@@ -949,6 +958,47 @@ static void test_rtti(void)
   call_func1(pexception_dtor, &e);
   call_func1(pbad_typeid_dtor, &b);
 
+  memcpy(&simple_class_sig0_rtti, &simple_class_rtti, sizeof(struct rtti_data));
+  simple_class_sig0_rtti.object_locator.signature = 0;
+  simple_class_sig0_rtti.base_descriptor[0].type_descriptor = RTTI_REF_SIG0(simple_class_sig0_rtti, type_info[0], base);
+  simple_class_sig0_rtti.base_array.bases[0] = RTTI_REF_SIG0(simple_class_sig0_rtti, base_descriptor[0], base);
+  simple_class_sig0_rtti.object_hierarchy.base_classes = RTTI_REF_SIG0(simple_class_sig0_rtti, base_array, base);
+  simple_class_sig0_rtti.object_locator.type_descriptor = RTTI_REF_SIG0(simple_class_sig0_rtti, type_info[0], base);
+  simple_class_sig0_rtti.object_locator.type_hierarchy = RTTI_REF_SIG0(simple_class_sig0_rtti, object_hierarchy, base);
+
+  memcpy(&child_class_sig0_rtti, &child_class_rtti, sizeof(struct rtti_data));
+  child_class_sig0_rtti.object_locator.signature = 0;
+  child_class_sig0_rtti.base_descriptor[0].type_descriptor = RTTI_REF_SIG0(child_class_sig0_rtti, type_info[1], base);
+  child_class_sig0_rtti.base_descriptor[1].type_descriptor = RTTI_REF_SIG0(child_class_sig0_rtti, type_info[0], base);
+  child_class_sig0_rtti.base_array.bases[0] = RTTI_REF_SIG0(child_class_sig0_rtti, base_descriptor[0], base);
+  child_class_sig0_rtti.base_array.bases[1] = RTTI_REF_SIG0(child_class_sig0_rtti, base_descriptor[1], base);
+  child_class_sig0_rtti.object_hierarchy.base_classes = RTTI_REF_SIG0(child_class_sig0_rtti, base_array, base);
+  child_class_sig0_rtti.object_locator.type_descriptor = RTTI_REF_SIG0(child_class_sig0_rtti, type_info[1], base);
+  child_class_sig0_rtti.object_locator.type_hierarchy = RTTI_REF_SIG0(child_class_sig0_rtti, object_hierarchy, base);
+
+  ti = p__RTtypeid(&simple_class_sig0);
+  ok (ti && ti->mangled && !strcmp(ti->mangled, "simple_class"),
+          "incorrect rtti data\n");
+
+  casted = p__RTCastToVoid(&simple_class_sig0);
+  ok (casted == (void*)&simple_class_sig0, "failed cast to void\n");
+
+  ti = p__RTtypeid(&child_class_sig0);
+  ok (ti && ti->mangled && !strcmp(ti->mangled, "child_class"),
+          "incorrect rtti data\n");
+
+  casted = p__RTCastToVoid(&child_class_sig0);
+  ok (casted == (void*)&child_class_sig0, "failed cast to void\n");
+
+  casted = p__RTDynamicCast(&child_class_sig0, 0, NULL, simple_class_sig0_rtti.type_info, 0);
+  if(casted)
+  {
+      ok (casted == (char*)&child_class_sig0+8, "failed cast to simple_class (%p %p)\n", casted, &child_class_sig0);
+  }
+
+  casted = p__RTDynamicCast(&child_class_sig0, 0, &child_class_sig0_rtti.type_info[0], &child_class_sig0_rtti.type_info[1], 0);
+  ok(casted == (char*)&child_class_sig0+4, "failed cast to child class (%p %p)\n", casted, &child_class_sig0);
+
   if(old_signature) {
       skip("signature==1 is not supported\n");
       return;