diff --git a/drivers/filesystems/udfs/misc.cpp b/drivers/filesystems/udfs/misc.cpp
index 75765fe90ce48..ecf704639aae9 100644
--- a/drivers/filesystems/udfs/misc.cpp
+++ b/drivers/filesystems/udfs/misc.cpp
@@ -188,7 +188,7 @@ UDFProcessException(
         } 
         else if ((ExceptionCode == STATUS_VERIFY_REQUIRED) &&
                  FlagOn(IrpContext->Flags, IRP_CONTEXT_FLAG_TOP_LEVEL) &&
-                 KeAreAllApcsDisabled()) {
+                 (KeGetCurrentIrql() >= APC_LEVEL)) {
                  
             ExceptionCode = UDFFsdPostRequest(IrpContext, Irp);
         }
diff --git a/drivers/filesystems/udfs/udffs.h b/drivers/filesystems/udfs/udffs.h
index 272046b907e62..c52e5f8db9c88 100644
--- a/drivers/filesystems/udfs/udffs.h
+++ b/drivers/filesystems/udfs/udffs.h
@@ -91,6 +91,11 @@ typedef FILE_ID                     *PFILE_ID;
 #undef MdlMappingNoExecute
 #define MdlMappingNoExecute 0
 #define NonPagedPoolNx NonPagedPool
+// POOL_NX_ALLOCATION (0x200) is a Windows 8+ flag not recognized on XP-based
+// systems. Passing it to ExInitialize*LookasideList would result in an invalid
+// pool type on Windows XP / POSReady 2009.
+#undef POOL_NX_ALLOCATION
+#define POOL_NX_ALLOCATION 0
 #endif
 
 // #define NDEBUG
diff --git a/drivers/filesystems/udfs/udfinit.cpp b/drivers/filesystems/udfs/udfinit.cpp
index 657034565142c..38248af9d2751 100644
--- a/drivers/filesystems/udfs/udfinit.cpp
+++ b/drivers/filesystems/udfs/udfinit.cpp
@@ -210,8 +210,11 @@ DriverEntry(
             FilterCallbacks.PreAcquireForSectionSynchronization = UDFFilterCallbackAcquireForCreateSection;
 
             RC = FsRtlRegisterFileSystemFilterCallbacks(DriverObject, &FilterCallbacks);
-            if (!NT_SUCCESS(RC))
-                try_return(RC);
+            if (!NT_SUCCESS(RC)) {
+                // On Windows XP, this call may fail. Treat as non-fatal.
+                UDFPrint(("UDF: FsRtlRegisterFileSystemFilterCallbacks failed with %x, continuing\n", RC));
+                RC = STATUS_SUCCESS;
+            }
 
             UDFPrint(("UDF: Create CD dev obj\n"));
             if (!NT_SUCCESS(RC = UDFCreateFsDeviceObject(UDF_FS_NAME_CD,