diff --git a/src/sys/device.c b/src/sys/device.c
index f90a91fa..c56f97c9 100644
--- a/src/sys/device.c
+++ b/src/sys/device.c
@@ -22,6 +22,8 @@ static NTSTATUS FspFsvolDeviceInit(PDEVICE_OBJECT DeviceObject);
 static VOID FspFsvolDeviceFini(PDEVICE_OBJECT DeviceObject);
 BOOLEAN FspDeviceRetain(PDEVICE_OBJECT DeviceObject);
 VOID FspDeviceRelease(PDEVICE_OBJECT DeviceObject);
+VOID FspFsctlDeviceVolumeCreated(PDEVICE_OBJECT DeviceObject);
+VOID FspFsctlDeviceVolumeDeleted(PDEVICE_OBJECT DeviceObject);
 NTSTATUS FspDeviceCopyList(
     PDEVICE_OBJECT **PDeviceObjects, PULONG PDeviceObjectCount);
 VOID FspDeviceDeleteList(
@@ -38,6 +40,8 @@ VOID FspDeviceDeleteAll(VOID);
 #pragma alloc_text(PAGE, FspFsvrtDeviceFini)
 #pragma alloc_text(PAGE, FspFsvolDeviceInit)
 #pragma alloc_text(PAGE, FspFsvolDeviceFini)
+#pragma alloc_text(PAGE, FspFsctlDeviceVolumeCreated)
+#pragma alloc_text(PAGE, FspFsctlDeviceVolumeDeleted)
 #pragma alloc_text(PAGE, FspDeviceCopyList)
 #pragma alloc_text(PAGE, FspDeviceDeleteList)
 #pragma alloc_text(PAGE, FspDeviceDeleteAll)
@@ -241,6 +245,30 @@ VOID FspDeviceRelease(PDEVICE_OBJECT DeviceObject)
         FspDeviceDelete(DeviceObject);
 }
 
+VOID FspFsctlDeviceVolumeCreated(PDEVICE_OBJECT DeviceObject)
+{
+    PAGED_CODE();
+
+    ASSERT(FspFsctlDeviceExtensionKind == FspDeviceExtension(DeviceObject)->Kind);
+    ASSERT(ExIsResourceAcquiredExclusiveLite(&FspDeviceExtension(DeviceObject)->Resource));
+
+    ULONG FsvrtDeviceObjectCount = FspFsctlDeviceExtension(DeviceObject)->FsvrtDeviceObjectCount++;
+    if (0 == FsvrtDeviceObjectCount)
+        IoRegisterFileSystem(DeviceObject);
+}
+
+VOID FspFsctlDeviceVolumeDeleted(PDEVICE_OBJECT DeviceObject)
+{
+    PAGED_CODE();
+
+    ASSERT(FspFsctlDeviceExtensionKind == FspDeviceExtension(DeviceObject)->Kind);
+    ASSERT(ExIsResourceAcquiredExclusiveLite(&FspDeviceExtension(DeviceObject)->Resource));
+
+    ULONG FsvrtDeviceObjectCount = --FspFsctlDeviceExtension(DeviceObject)->FsvrtDeviceObjectCount;
+    if (0 == FsvrtDeviceObjectCount)
+        IoUnregisterFileSystem(DeviceObject);
+}
+
 NTSTATUS FspDeviceCopyList(
     PDEVICE_OBJECT **PDeviceObjects, PULONG PDeviceObjectCount)
 {
@@ -250,7 +278,7 @@ NTSTATUS FspDeviceCopyList(
     ULONG DeviceObjectCount = 0;
 
     while (STATUS_BUFFER_TOO_SMALL == IoEnumerateDeviceObjectList(FspDriverObject,
-        DeviceObjects, DeviceObjectCount, &DeviceObjectCount))
+        DeviceObjects, sizeof *DeviceObjects * DeviceObjectCount, &DeviceObjectCount))
     {
         if (0 != DeviceObjects)
             ExFreePoolWithTag(DeviceObjects, FSP_TAG);
diff --git a/src/sys/driver.c b/src/sys/driver.c
index 965ee16d..ccaf13d6 100644
--- a/src/sys/driver.c
+++ b/src/sys/driver.c
@@ -116,10 +116,6 @@ NTSTATUS DriverEntry(
 #pragma prefast(suppress:28175, "We are a filesystem: ok to access FastIoDispatch")
     DriverObject->FastIoDispatch = &FspFastIoDispatch;
 
-    /* register our device objects as file systems */
-    IoRegisterFileSystem(FspFsctlDiskDeviceObject);
-    IoRegisterFileSystem(FspFsctlNetDeviceObject);
-
 #pragma prefast(suppress:28175, "We are in DriverEntry: ok to access DriverName")
     FSP_LEAVE("DriverName=\"%wZ\", RegistryPath=\"%wZ\"",
         &DriverObject->DriverName, RegistryPath);
diff --git a/src/sys/driver.h b/src/sys/driver.h
index d178899d..c563ab62 100644
--- a/src/sys/driver.h
+++ b/src/sys/driver.h
@@ -261,6 +261,7 @@ typedef struct
 typedef struct
 {
     FSP_DEVICE_EXTENSION Base;
+    ULONG FsvrtDeviceObjectCount;
 } FSP_FSCTL_DEVICE_EXTENSION;
 typedef struct
 {
@@ -311,6 +312,8 @@ NTSTATUS FspDeviceCreate(UINT32 Kind, ULONG ExtraSize,
 VOID FspDeviceDelete(PDEVICE_OBJECT DeviceObject);
 BOOLEAN FspDeviceRetain(PDEVICE_OBJECT DeviceObject);
 VOID FspDeviceRelease(PDEVICE_OBJECT DeviceObject);
+VOID FspFsctlDeviceVolumeCreated(PDEVICE_OBJECT DeviceObject);
+VOID FspFsctlDeviceVolumeDeleted(PDEVICE_OBJECT DeviceObject);
 NTSTATUS FspDeviceCopyList(
     PDEVICE_OBJECT **PDeviceObjects, PULONG PDeviceObjectCount);
 VOID FspDeviceDeleteList(
diff --git a/src/sys/fsctl.c b/src/sys/fsctl.c
index b9f61825..a430a931 100644
--- a/src/sys/fsctl.c
+++ b/src/sys/fsctl.c
@@ -133,7 +133,7 @@ static NTSTATUS FspFsctlCreateVolume(
         return STATUS_INSUFFICIENT_RESOURCES;
     RtlCopyMemory(SecurityDescriptorBuf, SecurityDescriptor, SecurityDescriptorSize);
 
-    /* create the virtual volume device */
+    /* prepare the device name and SDDL */
     PDEVICE_OBJECT FsvrtDeviceObject;
     UNICODE_STRING DeviceSddl;
     UNICODE_STRING DeviceName;
@@ -145,21 +145,33 @@ static NTSTATUS FspFsctlCreateVolume(
         Guid.Data4[0], Guid.Data4[1], Guid.Data4[2], Guid.Data4[3],
         Guid.Data4[4], Guid.Data4[5], Guid.Data4[6], Guid.Data4[7]);
     ASSERT(NT_SUCCESS(Result));
-    Result = FspDeviceCreateSecure(FspFsvrtDeviceExtensionKind, SecurityDescriptorSize,
-        &DeviceName, FILE_DEVICE_VIRTUAL_DISK,
-        &DeviceSddl, &FspFsvrtDeviceClassGuid,
-        &FsvrtDeviceObject);
-    if (NT_SUCCESS(Result))
+
+    /* create the virtual volume device */
+    FSP_FSCTL_DEVICE_EXTENSION *FsctlDeviceExtension = FspFsctlDeviceExtension(DeviceObject);
+    ExAcquireResourceExclusiveLite(&FsctlDeviceExtension->Base.Resource, TRUE);
+    try
     {
+        Result = FspDeviceCreateSecure(FspFsvrtDeviceExtensionKind, SecurityDescriptorSize,
+            &DeviceName, FILE_DEVICE_VIRTUAL_DISK,
+            &DeviceSddl, &FspFsvrtDeviceClassGuid,
+            &FsvrtDeviceObject);
+        if (NT_SUCCESS(Result))
+        {
 #pragma prefast(suppress:28175, "We are a filesystem: ok to access SectorSize")
-        FsvrtDeviceObject->SectorSize = Params.SectorSize;
-        FsvrtDeviceExtension = FspFsvrtDeviceExtension(FsvrtDeviceObject);
-        FsvrtDeviceExtension->FsctlDeviceObject = DeviceObject;
-        FsvrtDeviceExtension->VolumeParams = Params;
-        RtlCopyMemory(FsvrtDeviceExtension->SecurityDescriptorBuf,
-            SecurityDescriptorBuf, SecurityDescriptorSize);
-        ClearFlag(FsvrtDeviceObject->Flags, DO_DEVICE_INITIALIZING);
-        Irp->IoStatus.Information = DeviceName.Length + sizeof(WCHAR);
+            FsvrtDeviceObject->SectorSize = Params.SectorSize;
+            FsvrtDeviceExtension = FspFsvrtDeviceExtension(FsvrtDeviceObject);
+            FsvrtDeviceExtension->FsctlDeviceObject = DeviceObject;
+            FsvrtDeviceExtension->VolumeParams = Params;
+            RtlCopyMemory(FsvrtDeviceExtension->SecurityDescriptorBuf,
+                SecurityDescriptorBuf, SecurityDescriptorSize);
+            ClearFlag(FsvrtDeviceObject->Flags, DO_DEVICE_INITIALIZING);
+            Irp->IoStatus.Information = DeviceName.Length + sizeof(WCHAR);
+            FspFsctlDeviceVolumeCreated(DeviceObject);
+        }
+    }
+    finally
+    {
+        ExReleaseResourceLite(&FsctlDeviceExtension->Base.Resource);
     }
 
     /* free the temporary security descriptor */
@@ -292,12 +304,15 @@ static NTSTATUS FspFsvrtDeleteVolume(
 #pragma prefast(pop)
 
         /* release the file system device and virtual volume objects */
+        PDEVICE_OBJECT FsctlDeviceObject = FsvrtDeviceExtension->FsctlDeviceObject;
         PDEVICE_OBJECT FsvolDeviceObject = FsvrtDeviceExtension->FsvolDeviceObject;
         FsvrtDeviceExtension->FsvolDeviceObject = 0;
         if (0 != FsvolDeviceObject)
             FspDeviceRelease(FsvolDeviceObject);
         FspDeviceRelease(DeviceObject);
 
+        FspFsctlDeviceVolumeDeleted(FsctlDeviceObject);
+
         Result = STATUS_SUCCESS;
 
     exit:;