diff --git a/reactos/ntoskrnl/include/internal/ntoskrnl.h b/reactos/ntoskrnl/include/internal/ntoskrnl.h
index 7eef767a441..8ce0e52ab40 100644
--- a/reactos/ntoskrnl/include/internal/ntoskrnl.h
+++ b/reactos/ntoskrnl/include/internal/ntoskrnl.h
@@ -147,6 +147,24 @@ RtlReleaseCapturedUnicodeString(
 #define ProbeForReadLargeInteger(Ptr) ((LARGE_INTEGER)ProbeForReadGenericType(&(Ptr)->QuadPart, LONGLONG, 0))
 #define ProbeForReadUlargeInteger(Ptr) ((ULARGE_INTEGER)ProbeForReadGenericType(&(Ptr)->QuadPart, ULONGLONG, 0))
 
+/*
+ * Use IsKernelPointer to test whether a pointer points to the kernel address
+ * space
+ */
+#if defined(_X86_) || defined(_M_AMD64)
+
+/* for x86 and x86-64 the MSB is 1 so we can simply test on that */
+#define IsKernelPointer(Ptr) ((LONG_PTR)(Ptr) < 0)
+
+#elif defined(_IA64_)
+
+/* on Itanium if the 24 most significant bits are set, we're not dealing with
+   user mode pointers. */
+#define IsKernelPointer(Ptr)  (((ULONG_PTR)(Ptr) & 0xFFFFFF0000000000ULL) != 0)
+
+#else
+#error IsKernelPointer() needs to be defined for this architecture
+#endif
 
 #endif
 /*
diff --git a/reactos/ntoskrnl/ob/wait.c b/reactos/ntoskrnl/ob/wait.c
index 96f45bddb21..538cc42dcae 100644
--- a/reactos/ntoskrnl/ob/wait.c
+++ b/reactos/ntoskrnl/ob/wait.c
@@ -149,7 +149,7 @@ NtWaitForMultipleObjects(IN ULONG ObjectCount,
         DefaultObject = ObjectHeader->Type->DefaultObject;
 
         /* Check if it's the internal offset */
-        if ((LONG_PTR)DefaultObject >= 0)
+        if (!IsKernelPointer(DefaultObject))
         {
             /* Increase reference count */
             InterlockedIncrement(&ObjectHeader->PointerCount);
@@ -295,7 +295,7 @@ NtWaitForSingleObject(IN HANDLE ObjectHandle,
         WaitableObject = BODY_TO_HEADER(Object)->Type->DefaultObject;
 
         /* Is it an offset for internal objects? */
-        if ((LONG_PTR)WaitableObject >= 0)
+        if (!IsKernelPointer(WaitableObject))
         {
             /* Turn it into a pointer */
             WaitableObject = (PVOID)((ULONG_PTR)Object +
@@ -389,7 +389,7 @@ NtSignalAndWaitForSingleObject(IN HANDLE ObjectHandleToSignal,
     WaitableObject = BODY_TO_HEADER(WaitObj)->Type->DefaultObject;
 
     /* Handle internal offset */
-    if ((LONG_PTR)WaitableObject >= 0)
+    if (!IsKernelPointer(WaitableObject))
     {
         /* Get real pointer */
         WaitableObject = (PVOID)((ULONG_PTR)WaitObj +