diff --git a/src/exec/misc.asm b/src/exec/misc.asm
index a66917d..a45977d 100644
--- a/src/exec/misc.asm
+++ b/src/exec/misc.asm
@@ -5,9 +5,15 @@ setVobToTransient:
         resetStackoffset 0x68
         pusha
 
-        mov     ecx, [esi]
-        cmp     ecx, oCNpc__vftable
-        jnz     .back
+        mov     eax, [esi]
+        mov     ecx, esi
+        call    DWORD [eax]
+        push    eax
+        push    oCNpc__classDef
+        call    zCObject__CheckInheritance
+        add     esp, 0x8
+        test    eax, eax
+        jz      .back
 
         mov     eax, [esi+g1g2(0x7B0,0x770)]                               ; oCNpc.instanz
         test    eax, eax
@@ -478,9 +484,19 @@ fix_Hlp_GetNpc:
         mov     eax, [esi+zCPar_Symbol_offset_offset]
         test    eax, eax
         jz      g1g2(0x65880E,0x6EEE6E)
-        mov     eax, [eax]
-        cmp     eax, oCNpc__vftable
-        jnz     g1g2(0x65880E,0x6EEE6E)
+
+        push    ecx
+        mov     ecx, eax
+        mov     eax, [ecx]
+        call    DWORD [eax]
+        push    eax
+        push    oCNpc__classDef
+        call    zCObject__CheckInheritance
+        add     esp, 0x8
+        test    eax, eax
+        pop     ecx
+        jz      g1g2(0x65880E,0x6EEE6E)
+    verifyStackoffset 0x10
 
         ; Jump back
         push    edi
@@ -493,11 +509,18 @@ fix_Hlp_IsValidNpc:
     resetStackoffset 0x18
         test    eax, eax
         jz      .back
-        mov     eax, [eax]
-        cmp     eax, oCNpc__vftable
-        jz      .back
-        xor     eax, eax
-        jmp     .backClean
+
+        push    ecx
+        mov     ecx, eax
+        mov     eax, [ecx]
+        call    DWORD [eax]
+        push    eax
+        push    oCNpc__classDef
+        call    zCObject__CheckInheritance
+        add     esp, 0x8
+        test    eax, eax
+        pop     ecx
+        jz      .backClean
     verifyStackoffset 0x18
 
 .back:
@@ -512,11 +535,18 @@ fix_Hlp_IsValidItem:
     resetStackoffset 0x18
         test    eax, eax
         jz      .back
-        mov     eax, [eax]
-        cmp     eax, oCItem__vftable
-        jz      .back
-        xor     eax, eax
-        jmp     .backClean
+
+        push    ecx
+        mov     ecx, eax
+        mov     eax, [ecx]
+        call    DWORD [eax]
+        push    eax
+        push    oCItem__classDef
+        call    zCObject__CheckInheritance
+        add     esp, 0x8
+        test    eax, eax
+        pop     ecx
+        jz      .backClean
     verifyStackoffset 0x18
 
 .back:
diff --git a/src/inc/engine_g1.inc b/src/inc/engine_g1.inc
index 4f80f7d..12e67c1 100644
--- a/src/inc/engine_g1.inc
+++ b/src/inc/engine_g1.inc
@@ -81,8 +81,7 @@
     %define     oCGame__GetInfoManager                    0x638AE0     ; void
     %define     oCMissionManager_misMan                   0x8DAB2C     ; oCMissionManager*
     %define     oCNpc__classDef                           0x8DB408     ; zCClassDef
-    %define     oCNpc__vftable                            0x7DDF34     ; const
-    %define     oCItem__vftable                           0x7DD0CC     ; const
+    %define     oCItem__classDef                          0x8DAA80     ; zCClassDef
     %define     zCObject__CheckInheritance                0x470130     ; zCClassDef const *, zCClassDef const *
     %define     oCWorld__InsertInLists                    0x6D7670     ; zCVob *
     %define     oCWorld__RemoveFromLists                  0x6D7750     ; zCVob *
diff --git a/src/inc/engine_g2.inc b/src/inc/engine_g2.inc
index 3a5ef42..046d0ce 100644
--- a/src/inc/engine_g2.inc
+++ b/src/inc/engine_g2.inc
@@ -81,8 +81,7 @@
     %define     oCGame__GetInfoManager                    0x6C2C90     ; void
     %define     oCMissionManager_misMan                   0xAB1384     ; oCMissionManager*
     %define     oCNpc__classDef                           0xAB1E20     ; zCClassDef
-    %define     oCNpc__vftable                            0x83D724     ; const
-    %define     oCItem__vftable                           0x83C804     ; const
+    %define     oCItem__classDef                          0xAB1168     ; zCClassDef
     %define     zCObject__CheckInheritance                0x476E30     ; zCClassDef const *, zCClassDef const *
     %define     oCWorld__InsertInLists                    0x7808B0     ; zCVob *
     %define     oCWorld__RemoveFromLists                  0x780990     ; zCVob *