diff --git a/ntoskrnl/include/internal/io.h b/ntoskrnl/include/internal/io.h
index 806bd7dd4cd..289e81131c3 100644
--- a/ntoskrnl/include/internal/io.h
+++ b/ntoskrnl/include/internal/io.h
@@ -414,11 +414,11 @@ typedef struct _DRIVER_INFORMATION
 //
 typedef struct _IO_BUS_TYPE_GUID_LIST
 {
-    ULONG GuidCount;
     FAST_MUTEX Lock;
-    GUID Guids[1];
+    ULONG AllocatedCount;
+    ULONG GuidCount;
+    PGUID Guids;
 } IO_BUS_TYPE_GUID_LIST, *PIO_BUS_TYPE_GUID_LIST;
-extern PIO_BUS_TYPE_GUID_LIST IopBusTypeGuidList;
 
 //
 // Shutdown entry for registed devices
@@ -1445,7 +1445,7 @@ extern LIST_ENTRY IopErrorLogListHead;
 extern ULONG IopAutoReboot;
 extern ULONG IopNumTriageDumpDataBlocks;
 extern PVOID IopTriageDumpDataBlocks[64];
-extern PIO_BUS_TYPE_GUID_LIST PnpBusTypeGuidList;
+extern IO_BUS_TYPE_GUID_LIST PnpBusTypeGuidList;
 extern PDRIVER_OBJECT IopRootDriverObject;
 extern KSPIN_LOCK IopDeviceActionLock;
 extern LIST_ENTRY IopDeviceActionRequestList;
diff --git a/ntoskrnl/include/internal/tag.h b/ntoskrnl/include/internal/tag.h
index 616bffad763..c257f455a5f 100644
--- a/ntoskrnl/include/internal/tag.h
+++ b/ntoskrnl/include/internal/tag.h
@@ -89,6 +89,7 @@
 #define TAG_IO_DEVNODE          'donD'
 #define TAG_PNP_NOTIFY          'NPnP'
 #define TAG_PNP_ROOT            'RPnP'
+#define TAG_PNP_GUIDS           'GPnP'
 #define TAG_IO_RESOURCE         'CRSR'
 #define TAG_IO_TIMER            'MTOI'
 #define TAG_VPB                 ' BPV'
diff --git a/ntoskrnl/io/pnpmgr/pnpinit.c b/ntoskrnl/io/pnpmgr/pnpinit.c
index 258527be5de..4715f250cb8 100644
--- a/ntoskrnl/io/pnpmgr/pnpinit.c
+++ b/ntoskrnl/io/pnpmgr/pnpinit.c
@@ -444,10 +444,19 @@ IopInitializePlugPlayServices(VOID)
     if (!NT_SUCCESS(Status)) return Status;
 
     /* Initialize the Bus Type GUID List */
-    PnpBusTypeGuidList = ExAllocatePool(PagedPool, sizeof(IO_BUS_TYPE_GUID_LIST));
-    RtlZeroMemory(PnpBusTypeGuidList, sizeof(IO_BUS_TYPE_GUID_LIST));
-    ExInitializeFastMutex(&PnpBusTypeGuidList->Lock);
-
+    ExInitializeFastMutex(&PnpBusTypeGuidList.Lock);
+    PnpBusTypeGuidList.AllocatedCount = 8;
+    PnpBusTypeGuidList.GuidCount = 0;
+    PnpBusTypeGuidList.Guids = ExAllocatePoolWithTag(PagedPool,
+                                                     PnpBusTypeGuidList.AllocatedCount * sizeof(GUID),
+                                                     TAG_PNP_GUIDS);
+    if (PnpBusTypeGuidList.Guids == NULL)
+    {
+        DPRINT1("Failed to allocate PnP GUID buffer!\n");
+        KeBugCheckEx(PHASE1_INITIALIZATION_FAILED, STATUS_NO_MEMORY, 0, 0, 0);
+    }
+    RtlZeroMemory(PnpBusTypeGuidList.Guids, PnpBusTypeGuidList.AllocatedCount * sizeof(GUID));
+  
     /* Initialize PnP root relations (this is a syncronous operation) */
     PiQueueDeviceAction(Pdo, PiActionEnumRootDevices, NULL, NULL);
 
diff --git a/ntoskrnl/io/pnpmgr/pnpmgr.c b/ntoskrnl/io/pnpmgr/pnpmgr.c
index eac446f789d..e54b830a963 100644
--- a/ntoskrnl/io/pnpmgr/pnpmgr.c
+++ b/ntoskrnl/io/pnpmgr/pnpmgr.c
@@ -24,7 +24,7 @@ extern ULONG ExpInitializationPhase;
 /* DATA **********************************************************************/
 
 PDRIVER_OBJECT IopRootDriverObject;
-PIO_BUS_TYPE_GUID_LIST PnpBusTypeGuidList = NULL;
+IO_BUS_TYPE_GUID_LIST PnpBusTypeGuidList;
 
 /* FUNCTIONS *****************************************************************/
 
@@ -410,66 +410,67 @@ USHORT
 NTAPI
 IopGetBusTypeGuidIndex(LPGUID BusTypeGuid)
 {
-    USHORT i = 0, FoundIndex = 0xFFFF;
-    ULONG NewSize;
-    PVOID NewList;
+    USHORT i, FoundIndex = 0xFFFF;
+    ULONG NewAllocatedCount;
+    PGUID NewList;
 
     /* Acquire the lock */
-    ExAcquireFastMutex(&PnpBusTypeGuidList->Lock);
+    ExAcquireFastMutex(&PnpBusTypeGuidList.Lock);
 
     /* Loop all entries */
-    while (i < PnpBusTypeGuidList->GuidCount)
+    for (i = 0; i < PnpBusTypeGuidList.GuidCount; i++)
     {
          /* Try to find a match */
-         if (RtlCompareMemory(BusTypeGuid,
-                              &PnpBusTypeGuidList->Guids[i],
-                              sizeof(GUID)) == sizeof(GUID))
+         if (IsEqualGUID(BusTypeGuid, &PnpBusTypeGuidList.Guids[i]))
          {
               /* Found it */
               FoundIndex = i;
               goto Quickie;
          }
-         i++;
     }
 
     /* Check if we have to grow the list */
-    if (PnpBusTypeGuidList->GuidCount)
+    ASSERT(PnpBusTypeGuidList.GuidCount <= PnpBusTypeGuidList.AllocatedCount);
+    if (PnpBusTypeGuidList.GuidCount == PnpBusTypeGuidList.AllocatedCount)
     {
         /* Calculate the new size */
-        NewSize = sizeof(IO_BUS_TYPE_GUID_LIST) +
-                 (sizeof(GUID) * PnpBusTypeGuidList->GuidCount);
+        NewAllocatedCount = PnpBusTypeGuidList.AllocatedCount + 8;
 
         /* Allocate the new copy */
-        NewList = ExAllocatePool(PagedPool, NewSize);
-
+        NewList = ExAllocatePoolWithTag(PagedPool,
+                                        NewAllocatedCount * sizeof(GUID),
+                                        TAG_PNP_GUIDS);
         if (!NewList)
         {
             /* Fail */
             goto Quickie;
         }
 
-        /* Now copy them, decrease the size too */
-        NewSize -= sizeof(GUID);
-        RtlCopyMemory(NewList, PnpBusTypeGuidList, NewSize);
+        /* Copy the existing GUIDs to the new list and zero the rest */
+        RtlCopyMemory(NewList,
+                      PnpBusTypeGuidList.Guids,
+                      PnpBusTypeGuidList.GuidCount * sizeof(GUID));
+        RtlZeroMemory(&NewList[PnpBusTypeGuidList.GuidCount],
+                      (NewAllocatedCount - PnpBusTypeGuidList.GuidCount) * sizeof(GUID));
 
         /* Free the old list */
-        ExFreePool(PnpBusTypeGuidList);
+        ExFreePool(PnpBusTypeGuidList.Guids);
 
         /* Use the new buffer */
-        PnpBusTypeGuidList = NewList;
+        PnpBusTypeGuidList.Guids = NewList;
+        PnpBusTypeGuidList.AllocatedCount = NewAllocatedCount;
     }
 
     /* Copy the new GUID */
-    RtlCopyMemory(&PnpBusTypeGuidList->Guids[PnpBusTypeGuidList->GuidCount],
-                  BusTypeGuid,
-                  sizeof(GUID));
+    PnpBusTypeGuidList.Guids[PnpBusTypeGuidList.GuidCount] = *BusTypeGuid;
 
     /* The new entry is the index */
-    FoundIndex = (USHORT)PnpBusTypeGuidList->GuidCount;
-    PnpBusTypeGuidList->GuidCount++;
+    ASSERT(PnpBusTypeGuidList.GuidCount < MAXUSHORT);
+    FoundIndex = (USHORT)PnpBusTypeGuidList.GuidCount;
+    PnpBusTypeGuidList.GuidCount++;
 
 Quickie:
-    ExReleaseFastMutex(&PnpBusTypeGuidList->Lock);
+    ExReleaseFastMutex(&PnpBusTypeGuidList.Lock);
     return FoundIndex;
 }
 
@@ -1172,13 +1173,13 @@ PnpBusTypeGuidGet(IN USHORT Index,
     NTSTATUS Status = STATUS_SUCCESS;
 
     /* Acquire the lock */
-    ExAcquireFastMutex(&PnpBusTypeGuidList->Lock);
+    ExAcquireFastMutex(&PnpBusTypeGuidList.Lock);
 
     /* Validate size */
-    if (Index < PnpBusTypeGuidList->GuidCount)
+    if (Index < PnpBusTypeGuidList.GuidCount)
     {
         /* Copy the data */
-        RtlCopyMemory(BusTypeGuid, &PnpBusTypeGuidList->Guids[Index], sizeof(GUID));
+        RtlCopyMemory(BusTypeGuid, &PnpBusTypeGuidList.Guids[Index], sizeof(GUID));
     }
     else
     {
@@ -1187,7 +1188,7 @@ PnpBusTypeGuidGet(IN USHORT Index,
     }
 
     /* Release lock and return status */
-    ExReleaseFastMutex(&PnpBusTypeGuidList->Lock);
+    ExReleaseFastMutex(&PnpBusTypeGuidList.Lock);
     return Status;
 }