diff --git a/inc/winfsp/fsctl.h b/inc/winfsp/fsctl.h
index a08ada78..69926f9e 100644
--- a/inc/winfsp/fsctl.h
+++ b/inc/winfsp/fsctl.h
@@ -166,7 +166,8 @@ enum
     UINT32 UmFileContextIsFullContext:1;    /* user mode: FileContext parameter is FullContext */\
     UINT32 UmReservedFlags:6;\
     /* additional kernel-mode flags */\
-    UINT32 KmReservedFlags:8;\
+    UINT32 AllowOpenInKernelMode:1;         /* allow kernel mode to open files when possible */\
+    UINT32 KmReservedFlags:7;\
     WCHAR Prefix[FSP_FSCTL_VOLUME_PREFIX_SIZE / sizeof(WCHAR)]; /* UNC prefix (\Server\Share) */\
     WCHAR FileSystemName[FSP_FSCTL_VOLUME_FSNAME_SIZE / sizeof(WCHAR)];
 #define FSP_FSCTL_VOLUME_PARAMS_V1_FIELD_DEFN\
diff --git a/src/dotnet/FileSystemHost.cs b/src/dotnet/FileSystemHost.cs
index cbbca4e5..1bfd3d22 100644
--- a/src/dotnet/FileSystemHost.cs
+++ b/src/dotnet/FileSystemHost.cs
@@ -208,6 +208,11 @@ namespace Fsp
             get { return 0 != (_VolumeParams.Flags & VolumeParams.DeviceControl); }
             set { _VolumeParams.Flags |= (value ? VolumeParams.DeviceControl : 0); }
         }
+        public Boolean AllowOpenInKernelMode
+        {
+            get { return 0 != (_VolumeParams.Flags & VolumeParams.AllowOpenInKernelMode); }
+            set { _VolumeParams.Flags |= (value ? VolumeParams.AllowOpenInKernelMode : 0); }
+        }
         /// <summary>
         /// Gets or sets the prefix for a network file system.
         /// </summary>
diff --git a/src/dotnet/Interop.cs b/src/dotnet/Interop.cs
index 097ccb42..4e4d4829 100644
--- a/src/dotnet/Interop.cs
+++ b/src/dotnet/Interop.cs
@@ -51,6 +51,7 @@ namespace Fsp.Interop
         internal const UInt32 DeviceControl = 0x00008000;
         internal const UInt32 UmFileContextIsUserContext2 = 0x00010000;
         internal const UInt32 UmFileContextIsFullContext = 0x00020000;
+        internal const UInt32 AllowOpenInKernelMode = 0x01000000;
         internal const int PrefixSize = 192;
         internal const int FileSystemNameSize = 16;
 
diff --git a/src/sys/fileinfo.c b/src/sys/fileinfo.c
index aaaa2fb8..9835755a 100644
--- a/src/sys/fileinfo.c
+++ b/src/sys/fileinfo.c
@@ -1897,11 +1897,20 @@ BOOLEAN FspFastIoQueryOpen(
     PFILE_OBJECT FileObject = IrpSp->FileObject;
     FSP_FSCTL_FILE_INFO FileInfoBuf;
 
-    if (0 != FileObject->RelatedFileObject)
-        /* sorry, no can do relative opens in here */
+    DeviceObject = IrpSp->DeviceObject;
+
+    if (FspFsvolDeviceExtensionKind != FspDeviceExtension(DeviceObject)->Kind)
         FSP_RETURN(Result = FALSE);
 
-    Result = FspFileNodeTryGetFileInfoByName(IrpSp->DeviceObject, &FileObject->FileName, &FileInfoBuf);
+    /* do we allow kernel mode opens? */
+    if (!FspFsvolDeviceExtension(DeviceObject)->VolumeParams.AllowOpenInKernelMode)
+        FSP_RETURN(Result = FALSE);
+
+    /* is this a relative file open? */
+    if (0 != FileObject->RelatedFileObject)
+        FSP_RETURN(Result = FALSE);
+
+    Result = FspFileNodeTryGetFileInfoByName(DeviceObject, &FileObject->FileName, &FileInfoBuf);
     if (Result)
     {
         PVOID Buffer = Info;