diff --git a/ntoskrnl/fstub/fstubex.c b/ntoskrnl/fstub/fstubex.c
index 6e43f238e66..21a0dbd1561 100644
--- a/ntoskrnl/fstub/fstubex.c
+++ b/ntoskrnl/fstub/fstubex.c
@@ -1914,7 +1914,7 @@ IoGetBootDiskInformation(IN OUT PBOOTDISK_INFORMATION BootDiskInformation,
                                             NULL,
                                             0,
                                             &DiskGeometry,
-                                            sizeof(DISK_GEOMETRY),
+                                            sizeof(DiskGeometry),
                                             FALSE,
                                             &Event,
                                             &IoStatusBlock);
@@ -2023,7 +2023,7 @@ IoGetBootDiskInformation(IN OUT PBOOTDISK_INFORMATION BootDiskInformation,
                                                             NULL,
                                                             0,
                                                             &PartitionInformation,
-                                                            sizeof(PARTITION_INFORMATION_EX),
+                                                            sizeof(PartitionInformation),
                                                             FALSE,
                                                             &Event,
                                                             &IoStatusBlock);
@@ -2094,7 +2094,7 @@ IoGetBootDiskInformation(IN OUT PBOOTDISK_INFORMATION BootDiskInformation,
                                                             NULL,
                                                             0,
                                                             &PartitionInformation,
-                                                            sizeof(PARTITION_INFORMATION_EX),
+                                                            sizeof(PartitionInformation),
                                                             FALSE,
                                                             &Event,
                                                             &IoStatusBlock);
diff --git a/ntoskrnl/io/iomgr/arcname.c b/ntoskrnl/io/iomgr/arcname.c
index c36af33a5e8..bdb3e7b1324 100644
--- a/ntoskrnl/io/iomgr/arcname.c
+++ b/ntoskrnl/io/iomgr/arcname.c
@@ -274,7 +274,7 @@ IopCreateArcNamesCd(IN PLOADER_PARAMETER_BLOCK LoaderBlock)
                                                 NULL,
                                                 0,
                                                 &DeviceNumber,
-                                                sizeof(STORAGE_DEVICE_NUMBER),
+                                                sizeof(DeviceNumber),
                                                 FALSE,
                                                 &Event,
                                                 &IoStatusBlock);
@@ -499,7 +499,7 @@ IopCreateArcNamesDisk(IN PLOADER_PARAMETER_BLOCK LoaderBlock,
                                                     NULL,
                                                     0,
                                                     &DeviceNumber,
-                                                    sizeof(STORAGE_DEVICE_NUMBER),
+                                                    sizeof(DeviceNumber),
                                                     FALSE,
                                                     &Event,
                                                     &IoStatusBlock);
@@ -581,7 +581,7 @@ IopCreateArcNamesDisk(IN PLOADER_PARAMETER_BLOCK LoaderBlock,
                                             NULL,
                                             0,
                                             &DiskGeometry,
-                                            sizeof(DISK_GEOMETRY),
+                                            sizeof(DiskGeometry),
                                             FALSE,
                                             &Event,
                                             &IoStatusBlock);