diff --git a/UsbDk/ControlDevice.cpp b/UsbDk/ControlDevice.cpp
index a244a31..ab2b7de 100644
--- a/UsbDk/ControlDevice.cpp
+++ b/UsbDk/ControlDevice.cpp
@@ -1025,9 +1025,9 @@ NTSTATUS CUsbDkControlDevice::AddRedirectionToSet(const USB_DK_DEVICE_ID &Device
     return STATUS_SUCCESS;
 }
 
-NTSTATUS CUsbDkControlDevice::RemoveRedirect(const USB_DK_DEVICE_ID &DeviceId)
+NTSTATUS CUsbDkControlDevice::RemoveRedirect(const USB_DK_DEVICE_ID &DeviceId, ULONG pid)
 {
-    if (NotifyRedirectorRemovalStarted(DeviceId))
+    if (NotifyRedirectorRemovalStarted(DeviceId, pid))
     {
         auto res = ResetUsbDevice(DeviceId, false);
         if (NT_SUCCESS(res))
@@ -1079,9 +1079,8 @@ bool CUsbDkControlDevice::NotifyRedirectorAttached(CRegText *DeviceID, CRegText
     return m_Redirections.ModifyOne(&ID, [RedirectorDevice](CUsbDkRedirection *R){ R->NotifyRedirectorCreated(RedirectorDevice); });
 }
 
-bool CUsbDkControlDevice::NotifyRedirectorRemovalStarted(const USB_DK_DEVICE_ID &ID)
+bool CUsbDkControlDevice::NotifyRedirectorRemovalStarted(const USB_DK_DEVICE_ID &ID, ULONG pid)
 {
-    ULONG pid = (ULONG)(ULONG_PTR)PsGetCurrentProcessId();
     return m_Redirections.ModifyOne(&ID, [](CUsbDkRedirection *R){ R->NotifyRedirectionRemovalStarted(); }, pid);
 }
 
diff --git a/UsbDk/ControlDevice.h b/UsbDk/ControlDevice.h
index 9223036..1ed72a7 100644
--- a/UsbDk/ControlDevice.h
+++ b/UsbDk/ControlDevice.h
@@ -274,7 +274,7 @@ class CUsbDkControlDevice : private CWdfControlDevice, public CAllocatable<USBDK
 
     void ClearHideRules();
 
-    NTSTATUS RemoveRedirect(const USB_DK_DEVICE_ID &DeviceId);
+    NTSTATUS RemoveRedirect(const USB_DK_DEVICE_ID &DeviceId, ULONG pid);
     NTSTATUS GetConfigurationDescriptor(const USB_DK_CONFIG_DESCRIPTOR_REQUEST &Request,
                                         PUSB_CONFIGURATION_DESCRIPTOR Descriptor,
                                         size_t *OutputBuffLen);
@@ -309,7 +309,7 @@ class CUsbDkControlDevice : private CWdfControlDevice, public CAllocatable<USBDK
    }
 
     bool NotifyRedirectorAttached(CRegText *DeviceID, CRegText *InstanceID, CUsbDkFilterDevice *RedirectorDevice);
-    bool NotifyRedirectorRemovalStarted(const USB_DK_DEVICE_ID &ID);
+    bool NotifyRedirectorRemovalStarted(const USB_DK_DEVICE_ID &ID, ULONG pid);
     bool WaitForDetachment(const USB_DK_DEVICE_ID &ID);
 
 private:
diff --git a/UsbDk/FilterDevice.cpp b/UsbDk/FilterDevice.cpp
index 22d4383..7bbabed 100644
--- a/UsbDk/FilterDevice.cpp
+++ b/UsbDk/FilterDevice.cpp
@@ -86,12 +86,33 @@ NTSTATUS CUsbDkFilterDeviceInit::Configure(ULONG InstanceNumber)
     SetFileEventCallbacks([](_In_ WDFDEVICE Device, _In_ WDFREQUEST Request, _In_ WDFFILEOBJECT FileObject)
                           {
                                 UNREFERENCED_PARAMETER(FileObject);
-                                UsbDkFilterGetContext(Device)->UsbDkFilter->OnFileCreate(Request);
+                                auto filter = UsbDkFilterGetContext(Device)->UsbDkFilter;
+                                filter->m_open_count.AddRef();
+                                filter->OnFileCreate(Request);
                           },
                           [](_In_ WDFFILEOBJECT FileObject)
                           {
                                 WDFDEVICE Device = WdfFileObjectGetDevice(FileObject);
-                                Strategy(Device)->OnClose();
+                                auto filter = UsbDkFilterGetContext(Device)->UsbDkFilter;
+                                ULONG pid = 0; // zero means always match
+
+                                // Check PID only if there are multiple open references to the file.
+                                // If this was the last reference, always close the redirection.
+                                //
+                                // This callback function might run in a different process-context
+                                // than the initiator process, therefore the 'current process ID'
+                                // isn't always the ID of the 'owning' process.
+                                //
+                                // In the worst case, the USB redirection will be kept until the last
+                                // open file handle to the device is closed.
+                                //
+                                // From KMDF 1.21, there's a new method that should give us the expected ID:
+                                // WdfFileObjectGetInitiatorProcessId(FileObject)
+
+                                if (filter->m_open_count.Release()) {
+                                    pid = (ULONG)(ULONG_PTR)PsGetCurrentProcessId();
+                                }
+                                Strategy(Device)->OnClose(pid);
                           },
                           WDF_NO_EVENT_CALLBACK);
 
diff --git a/UsbDk/FilterDevice.h b/UsbDk/FilterDevice.h
index 76b38ca..1de5597 100644
--- a/UsbDk/FilterDevice.h
+++ b/UsbDk/FilterDevice.h
@@ -176,6 +176,9 @@ class CUsbDkFilterDevice : public CWdfDevice,
     { m_SerialNumber = Number; }
 
     void OnFileCreate(WDFREQUEST Request);
+
+    CWdmRefCounter m_open_count;
+
 private:
     ~CUsbDkFilterDevice()
     {
diff --git a/UsbDk/FilterStrategy.h b/UsbDk/FilterStrategy.h
index 82a664c..fdab0b0 100644
--- a/UsbDk/FilterStrategy.h
+++ b/UsbDk/FilterStrategy.h
@@ -62,7 +62,8 @@ class CUsbDkFilterStrategy
     CUsbDkControlDevice* GetControlDevice()
     { return m_ControlDevice; }
 
-    virtual void OnClose(){}
+    virtual void OnClose(ULONG pid)
+    { UNREFERENCED_PARAMETER(pid); }
 
 protected:
     CUsbDkFilterDevice *m_Owner = nullptr;
diff --git a/UsbDk/RedirectorStrategy.cpp b/UsbDk/RedirectorStrategy.cpp
index f8755f3..262db43 100644
--- a/UsbDk/RedirectorStrategy.cpp
+++ b/UsbDk/RedirectorStrategy.cpp
@@ -83,7 +83,7 @@ NTSTATUS CUsbDkRedirectorStrategy::Create(CUsbDkFilterDevice *Owner)
     return status;
 }
 
-using USBDK_REDIRECTOR_REQUEST_CONTEXT = struct : public USBDK_TARGET_REQUEST_CONTEXT
+struct USBDK_REDIRECTOR_REQUEST_CONTEXT : public USBDK_TARGET_REQUEST_CONTEXT
 {
     bool PreprocessingDone;
 
@@ -626,13 +626,13 @@ size_t CUsbDkRedirectorStrategy::GetRequestContextSize()
     return sizeof(USBDK_REDIRECTOR_REQUEST_CONTEXT);
 }
 
-void CUsbDkRedirectorStrategy::OnClose()
+void CUsbDkRedirectorStrategy::OnClose(ULONG pid)
 {
     USB_DK_DEVICE_ID ID;
     UsbDkFillIDStruct(&ID, *m_DeviceID->begin(), *m_InstanceID->begin());
     TraceEvents(TRACE_LEVEL_INFORMATION, TRACE_REDIRECTOR, "%!FUNC!");
 
-    auto status = m_ControlDevice->RemoveRedirect(ID);
+    auto status = m_ControlDevice->RemoveRedirect(ID, pid);
     if (!NT_SUCCESS(status))
     {
         TraceEvents(TRACE_LEVEL_ERROR, TRACE_REDIRECTOR, "%!FUNC! RemoveRedirect failed: %!STATUS!", status);
diff --git a/UsbDk/RedirectorStrategy.h b/UsbDk/RedirectorStrategy.h
index 31d07c0..d78c05d 100644
--- a/UsbDk/RedirectorStrategy.h
+++ b/UsbDk/RedirectorStrategy.h
@@ -75,7 +75,7 @@ class CUsbDkRedirectorStrategy : public CUsbDkHiderStrategy
                                        size_t InputBufferLength,
                                        ULONG IoControlCode) override;
 
-    virtual void OnClose() override;
+    virtual void OnClose(ULONG pid) override;
 
     void SetDeviceID(CRegText *DevID)
     { m_DeviceID = DevID; }
diff --git a/UsbDk/UsbTarget.h b/UsbDk/UsbTarget.h
index 9c2a3fa..eec896a 100644
--- a/UsbDk/UsbTarget.h
+++ b/UsbDk/UsbTarget.h
@@ -28,7 +28,7 @@
 #include "Urb.h"
 #include "WdfRequest.h"
 
-using USBDK_TARGET_REQUEST_CONTEXT = struct : public WDF_REQUEST_CONTEXT
+struct USBDK_TARGET_REQUEST_CONTEXT : public WDF_REQUEST_CONTEXT
 {
     ULONG64 RequestId;
 };