diff --git a/ntoskrnl/fstub/disksup.c b/ntoskrnl/fstub/disksup.c
index a27b8c35b8d..0903ffbbbf2 100644
--- a/ntoskrnl/fstub/disksup.c
+++ b/ntoskrnl/fstub/disksup.c
@@ -1768,7 +1768,7 @@ FASTCALL
 xHalIoReadPartitionTable(IN PDEVICE_OBJECT DeviceObject,
                          IN ULONG SectorSize,
                          IN BOOLEAN ReturnRecognizedPartitions,
-                         IN OUT PDRIVE_LAYOUT_INFORMATION *PartitionBuffer)
+                         OUT PDRIVE_LAYOUT_INFORMATION *PartitionBuffer)
 {
     KEVENT Event;
     IO_STATUS_BLOCK IoStatusBlock;
@@ -2697,7 +2697,7 @@ FASTCALL
 IoReadPartitionTable(IN PDEVICE_OBJECT DeviceObject,
                      IN ULONG SectorSize,
                      IN BOOLEAN ReturnRecognizedPartitions,
-                     IN OUT PDRIVE_LAYOUT_INFORMATION *PartitionBuffer)
+                     OUT PDRIVE_LAYOUT_INFORMATION *PartitionBuffer)
 {
     return HALDISPATCH->HalIoReadPartitionTable(DeviceObject,
                                                 SectorSize,
diff --git a/ntoskrnl/fstub/fstubex.c b/ntoskrnl/fstub/fstubex.c
index da965535aba..0ef2a04ae7e 100644
--- a/ntoskrnl/fstub/fstubex.c
+++ b/ntoskrnl/fstub/fstubex.c
@@ -2277,7 +2277,7 @@ Cleanup:
 NTSTATUS
 NTAPI
 IoReadPartitionTableEx(IN PDEVICE_OBJECT DeviceObject,
-                       IN PDRIVE_LAYOUT_INFORMATION_EX* DriveLayout)
+                       OUT PDRIVE_LAYOUT_INFORMATION_EX* DriveLayout)
 {
     NTSTATUS Status;
     PDISK_INFORMATION Disk;
diff --git a/ntoskrnl/include/internal/hal.h b/ntoskrnl/include/internal/hal.h
index d7e0e47b57d..2b2e89ca5bd 100644
--- a/ntoskrnl/include/internal/hal.h
+++ b/ntoskrnl/include/internal/hal.h
@@ -31,7 +31,7 @@ FASTCALL
 xHalIoReadPartitionTable(IN PDEVICE_OBJECT DeviceObject,
                          IN ULONG SectorSize,
                          IN BOOLEAN ReturnRecognizedPartitions,
-                         IN OUT PDRIVE_LAYOUT_INFORMATION *PartitionBuffer);
+                         OUT PDRIVE_LAYOUT_INFORMATION *PartitionBuffer);
 
 NTSTATUS
 FASTCALL