diff --git a/dlls/mountmgr.sys/device.c b/dlls/mountmgr.sys/device.c
index 9036654832c..00b59ed617c 100644
--- a/dlls/mountmgr.sys/device.c
+++ b/dlls/mountmgr.sys/device.c
@@ -568,6 +568,22 @@ NTSTATUS remove_dos_device( int letter, const char *udi )
     return STATUS_NO_SUCH_DEVICE;
 }
 
+/* query information about an existing dos drive, by letter or udi */
+NTSTATUS query_dos_device( int letter, DWORD *type, const char **device, const char **mount_point )
+{
+    struct dos_drive *drive;
+
+    LIST_FOR_EACH_ENTRY( drive, &drives_list, struct dos_drive, entry )
+    {
+        if (drive->drive != letter) continue;
+        if (type) *type = drive->type;
+        if (device) *device = drive->unix_device;
+        if (mount_point) *mount_point = drive->unix_mount;
+        return STATUS_SUCCESS;
+    }
+    return STATUS_NO_SUCH_DEVICE;
+}
+
 /* handler for ioctls on the harddisk device */
 static NTSTATUS WINAPI harddisk_ioctl( DEVICE_OBJECT *device, IRP *irp )
 {
diff --git a/dlls/mountmgr.sys/mountmgr.c b/dlls/mountmgr.sys/mountmgr.c
index c633588217f..3c1aa88668b 100644
--- a/dlls/mountmgr.sys/mountmgr.c
+++ b/dlls/mountmgr.sys/mountmgr.c
@@ -265,6 +265,61 @@ static NTSTATUS define_unix_drive( const void *in_buff, SIZE_T insize )
     }
 }
 
+/* implementation of IOCTL_MOUNTMGR_QUERY_UNIX_DRIVE */
+static NTSTATUS query_unix_drive( const void *in_buff, SIZE_T insize,
+                                  void *out_buff, SIZE_T outsize, IO_STATUS_BLOCK *iosb )
+{
+    const struct mountmgr_unix_drive *input = in_buff;
+    struct mountmgr_unix_drive *output = out_buff;
+    const char *device, *mount_point;
+    int letter = tolowerW( input->letter );
+    NTSTATUS status;
+    DWORD size, type;
+    char *ptr;
+
+    if (letter < 'a' || letter > 'z') return STATUS_INVALID_PARAMETER;
+
+    if ((status = query_dos_device( letter - 'a', &type, &device, &mount_point ))) return status;
+
+    size = sizeof(*output);
+    if (device) size += strlen(device) + 1;
+    if (mount_point) size += strlen(mount_point) + 1;
+
+    if (size > outsize)
+    {
+        if (size >= FIELD_OFFSET( struct mountmgr_unix_drive, size ) + sizeof(output->size))
+            output->size = size;
+        iosb->Information = FIELD_OFFSET( struct mountmgr_unix_drive, size ) + sizeof(output->size);
+        return STATUS_MORE_ENTRIES;
+    }
+    output->size = size;
+    output->letter = letter;
+    output->type = type;
+    ptr = (char *)(output + 1);
+
+    if (mount_point)
+    {
+        output->mount_point_offset = ptr - (char *)output;
+        strcpy( ptr, mount_point );
+        ptr += strlen(ptr) + 1;
+    }
+    else output->mount_point_offset = 0;
+
+    if (device)
+    {
+        output->device_offset = ptr - (char *)output;
+        strcpy( ptr, device );
+        ptr += strlen(ptr) + 1;
+    }
+    else output->device_offset = 0;
+
+    TRACE( "returning %c: dev %s mount %s type %u\n",
+           letter, debugstr_a(device), debugstr_a(mount_point), type );
+
+    iosb->Information = ptr - (char *)output;
+    return STATUS_SUCCESS;
+}
+
 /* handler for ioctls on the mount manager device */
 static NTSTATUS WINAPI mountmgr_ioctl( DEVICE_OBJECT *device, IRP *irp )
 {
@@ -293,6 +348,15 @@ static NTSTATUS WINAPI mountmgr_ioctl( DEVICE_OBJECT *device, IRP *irp )
         irp->IoStatus.u.Status = define_unix_drive( irpsp->Parameters.DeviceIoControl.Type3InputBuffer,
                                                     irpsp->Parameters.DeviceIoControl.InputBufferLength );
         break;
+    case IOCTL_MOUNTMGR_QUERY_UNIX_DRIVE:
+        if (irpsp->Parameters.DeviceIoControl.InputBufferLength < sizeof(struct mountmgr_unix_drive))
+            return STATUS_INVALID_PARAMETER;
+        irp->IoStatus.u.Status = query_unix_drive( irpsp->Parameters.DeviceIoControl.Type3InputBuffer,
+                                                   irpsp->Parameters.DeviceIoControl.InputBufferLength,
+                                                   irp->MdlAddress->StartVa,
+                                                   irpsp->Parameters.DeviceIoControl.OutputBufferLength,
+                                                   &irp->IoStatus );
+        break;
     default:
         FIXME( "ioctl %x not supported\n", irpsp->Parameters.DeviceIoControl.IoControlCode );
         irp->IoStatus.u.Status = STATUS_NOT_SUPPORTED;
diff --git a/dlls/mountmgr.sys/mountmgr.h b/dlls/mountmgr.sys/mountmgr.h
index 1b4b3f632fc..63e9b75da10 100644
--- a/dlls/mountmgr.sys/mountmgr.h
+++ b/dlls/mountmgr.sys/mountmgr.h
@@ -43,6 +43,7 @@ extern void initialize_diskarbitration(void);
 extern NTSTATUS add_dos_device( int letter, const char *udi, const char *device,
                                 const char *mount_point, DWORD type );
 extern NTSTATUS remove_dos_device( int letter, const char *udi );
+extern NTSTATUS query_dos_device( int letter, DWORD *type, const char **device, const char **mount_point );
 extern NTSTATUS WINAPI harddisk_driver_entry( DRIVER_OBJECT *driver, UNICODE_STRING *path );
 
 /* mount point functions */
diff --git a/include/ddk/mountmgr.h b/include/ddk/mountmgr.h
index 05eeeac282c..f0e836f6e11 100644
--- a/include/ddk/mountmgr.h
+++ b/include/ddk/mountmgr.h
@@ -53,6 +53,7 @@ static const WCHAR MOUNTMGR_DOS_DEVICE_NAME[] = {'\\','\\','.','\\','M','o','u',
 #ifdef WINE_MOUNTMGR_EXTENSIONS
 
 #define IOCTL_MOUNTMGR_DEFINE_UNIX_DRIVE CTL_CODE(MOUNTMGRCONTROLTYPE, 32, METHOD_BUFFERED, FILE_READ_ACCESS | FILE_WRITE_ACCESS)
+#define IOCTL_MOUNTMGR_QUERY_UNIX_DRIVE  CTL_CODE(MOUNTMGRCONTROLTYPE, 33, METHOD_BUFFERED, FILE_READ_ACCESS)
 
 struct mountmgr_unix_drive
 {