diff --git a/build/VStudio/winfsp_dll.vcxproj b/build/VStudio/winfsp_dll.vcxproj
index 66962919..85852f6e 100644
--- a/build/VStudio/winfsp_dll.vcxproj
+++ b/build/VStudio/winfsp_dll.vcxproj
@@ -100,7 +100,7 @@
       </PrecompiledHeader>
       <WarningLevel>Level3</WarningLevel>
       <Optimization>Disabled</Optimization>
-      <PreprocessorDefinitions>WIN32;_DEBUG;_WINDOWS;_USRDLL;WINFSPDLL_EXPORTS;%(PreprocessorDefinitions)</PreprocessorDefinitions>
+      <PreprocessorDefinitions>WINFSP_DLL_INTERNAL;WIN32;_DEBUG;_WINDOWS;_USRDLL;WINFSPDLL_EXPORTS;%(PreprocessorDefinitions)</PreprocessorDefinitions>
       <SDLCheck>true</SDLCheck>
       <AdditionalIncludeDirectories>..\..\inc;..\..\src</AdditionalIncludeDirectories>
     </ClCompile>
@@ -115,7 +115,7 @@
       </PrecompiledHeader>
       <WarningLevel>Level3</WarningLevel>
       <Optimization>Disabled</Optimization>
-      <PreprocessorDefinitions>_DEBUG;_WINDOWS;_USRDLL;WINFSPDLL_EXPORTS;%(PreprocessorDefinitions)</PreprocessorDefinitions>
+      <PreprocessorDefinitions>WINFSP_DLL_INTERNAL;_DEBUG;_WINDOWS;_USRDLL;WINFSPDLL_EXPORTS;%(PreprocessorDefinitions)</PreprocessorDefinitions>
       <SDLCheck>true</SDLCheck>
       <AdditionalIncludeDirectories>..\..\inc;..\..\src</AdditionalIncludeDirectories>
     </ClCompile>
@@ -132,7 +132,7 @@
       <Optimization>MaxSpeed</Optimization>
       <FunctionLevelLinking>true</FunctionLevelLinking>
       <IntrinsicFunctions>true</IntrinsicFunctions>
-      <PreprocessorDefinitions>WIN32;NDEBUG;_WINDOWS;_USRDLL;WINFSPDLL_EXPORTS;%(PreprocessorDefinitions)</PreprocessorDefinitions>
+      <PreprocessorDefinitions>WINFSP_DLL_INTERNAL;WIN32;NDEBUG;_WINDOWS;_USRDLL;WINFSPDLL_EXPORTS;%(PreprocessorDefinitions)</PreprocessorDefinitions>
       <SDLCheck>true</SDLCheck>
       <AdditionalIncludeDirectories>..\..\inc;..\..\src</AdditionalIncludeDirectories>
     </ClCompile>
@@ -151,7 +151,7 @@
       <Optimization>MaxSpeed</Optimization>
       <FunctionLevelLinking>true</FunctionLevelLinking>
       <IntrinsicFunctions>true</IntrinsicFunctions>
-      <PreprocessorDefinitions>NDEBUG;_WINDOWS;_USRDLL;WINFSPDLL_EXPORTS;%(PreprocessorDefinitions)</PreprocessorDefinitions>
+      <PreprocessorDefinitions>WINFSP_DLL_INTERNAL;NDEBUG;_WINDOWS;_USRDLL;WINFSPDLL_EXPORTS;%(PreprocessorDefinitions)</PreprocessorDefinitions>
       <SDLCheck>true</SDLCheck>
       <AdditionalIncludeDirectories>..\..\inc;..\..\src</AdditionalIncludeDirectories>
     </ClCompile>
diff --git a/build/VStudio/winfsp_sys.vcxproj b/build/VStudio/winfsp_sys.vcxproj
index a1c9f1bf..a5c3ae88 100644
--- a/build/VStudio/winfsp_sys.vcxproj
+++ b/build/VStudio/winfsp_sys.vcxproj
@@ -97,6 +97,7 @@
   <ItemDefinitionGroup Condition="'$(Configuration)|$(Platform)'=='Debug|Win32'">
     <ClCompile>
       <AdditionalIncludeDirectories>..\..\inc;..\..\src;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
+      <PreprocessorDefinitions>WINFSP_SYS_INTERNAL; _X86_=1;i386=1;STD_CALL;%(PreprocessorDefinitions)</PreprocessorDefinitions>
     </ClCompile>
     <Link>
       <AdditionalDependencies>wdmsec.lib;%(AdditionalDependencies)</AdditionalDependencies>
@@ -105,6 +106,7 @@
   <ItemDefinitionGroup Condition="'$(Configuration)|$(Platform)'=='Release|Win32'">
     <ClCompile>
       <AdditionalIncludeDirectories>..\..\inc;..\..\src;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
+      <PreprocessorDefinitions>WINFSP_SYS_INTERNAL; _X86_=1;i386=1;STD_CALL;%(PreprocessorDefinitions)</PreprocessorDefinitions>
     </ClCompile>
     <Link>
       <AdditionalDependencies>wdmsec.lib;%(AdditionalDependencies)</AdditionalDependencies>
@@ -113,6 +115,7 @@
   <ItemDefinitionGroup Condition="'$(Configuration)|$(Platform)'=='Debug|x64'">
     <ClCompile>
       <AdditionalIncludeDirectories>..\..\inc;..\..\src;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
+      <PreprocessorDefinitions>WINFSP_SYS_INTERNAL; _WIN64;_AMD64_;AMD64;%(PreprocessorDefinitions)</PreprocessorDefinitions>
     </ClCompile>
     <Link>
       <AdditionalDependencies>wdmsec.lib;%(AdditionalDependencies)</AdditionalDependencies>
@@ -121,6 +124,7 @@
   <ItemDefinitionGroup Condition="'$(Configuration)|$(Platform)'=='Release|x64'">
     <ClCompile>
       <AdditionalIncludeDirectories>..\..\inc;..\..\src;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
+      <PreprocessorDefinitions>WINFSP_SYS_INTERNAL; _WIN64;_AMD64_;AMD64;%(PreprocessorDefinitions)</PreprocessorDefinitions>
     </ClCompile>
     <Link>
       <AdditionalDependencies>wdmsec.lib;%(AdditionalDependencies)</AdditionalDependencies>
diff --git a/inc/winfsp/fsctl.h b/inc/winfsp/fsctl.h
index 0fbdb986..facd8b46 100644
--- a/inc/winfsp/fsctl.h
+++ b/inc/winfsp/fsctl.h
@@ -92,13 +92,13 @@ static inline const FSP_TRANSACT_RSP *FspFsctlTransactConsumeResponse(
     return NextResponse <= ResponseBufEnd ? NextResponse : 0;
 }
 
-#if !defined(WINFSP_SYS_DRIVER_H_INTERNAL)
-NTSTATUS FspFsctlCreateVolume(PWSTR DevicePath, PSECURITY_DESCRIPTOR SecurityDescriptor,
+#if !defined(WINFSP_SYS_INTERNAL)
+FSP_API NTSTATUS FspFsctlCreateVolume(PWSTR DevicePath, PSECURITY_DESCRIPTOR SecurityDescriptor,
     PHANDLE *PVolumeHandle);
-NTSTATUS FspFsctlOpenVolume(PWSTR VolumePath,
+FSP_API NTSTATUS FspFsctlOpenVolume(PWSTR VolumePath,
     PHANDLE *PVolumeHandle);
-NTSTATUS FspFsctlDeleteVolume(HANDLE VolumeHandle);
-NTSTATUS FspFsctlTransact(HANDLE VolumeHandle,
+FSP_API NTSTATUS FspFsctlDeleteVolume(HANDLE VolumeHandle);
+FSP_API NTSTATUS FspFsctlTransact(HANDLE VolumeHandle,
     FSP_TRANSACT_RSP *ResponseBuf, SIZE_T ResponseBufSize,
     FSP_TRANSACT_REQ *RequestBuf, SIZE_T *PRequestBufSize);
 #endif
diff --git a/inc/winfsp/winfsp.h b/inc/winfsp/winfsp.h
index dff14250..e37a3bba 100644
--- a/inc/winfsp/winfsp.h
+++ b/inc/winfsp/winfsp.h
@@ -13,6 +13,12 @@
 #include <winternl.h>
 #include <ntstatus.h>
 
+#if defined(WINFSP_DLL_INTERNAL)
+#define FSP_API                         __declspec(dllexport)
+#else
+#define FSP_API                         __declspec(dllimport)
+#endif
+
 NTSTATUS FspNtStatusFromWin32(DWORD Error);
 
 #endif
diff --git a/src/dll/fsctl.c b/src/dll/fsctl.c
index 0509155d..38297231 100644
--- a/src/dll/fsctl.c
+++ b/src/dll/fsctl.c
@@ -16,7 +16,7 @@ static inline VOID GlobalDevicePath(PWCHAR DevicePathBuf, SIZE_T DevicePathSize,
         L'\\' == DevicePath[0] ? GLOBALROOT "%S" : GLOBALROOT "\\Device\\%S", DevicePath);
 }
 
-NTSTATUS FspFsctlCreateVolume(PWSTR DevicePath, PSECURITY_DESCRIPTOR SecurityDescriptor,
+FSP_API NTSTATUS FspFsctlCreateVolume(PWSTR DevicePath, PSECURITY_DESCRIPTOR SecurityDescriptor,
     PHANDLE *PVolumeHandle)
 {
     NTSTATUS Result = STATUS_SUCCESS;
@@ -46,7 +46,7 @@ NTSTATUS FspFsctlCreateVolume(PWSTR DevicePath, PSECURITY_DESCRIPTOR SecurityDes
     }
 
     DeviceHandle = CreateFileW(DevicePathBuf,
-        0, FILE_SHARE_WRITE | FILE_SHARE_WRITE | FILE_SHARE_DELETE, 0, OPEN_EXISTING, 0, 0);
+        0, FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE, 0, OPEN_EXISTING, 0, 0);
     if (INVALID_HANDLE_VALUE == DeviceHandle)
     {
         Result = FspNtStatusFromWin32(GetLastError());
@@ -70,7 +70,7 @@ exit:
     return Result;
 }
 
-NTSTATUS FspFsctlOpenVolume(PWSTR VolumePath,
+FSP_API NTSTATUS FspFsctlOpenVolume(PWSTR VolumePath,
     PHANDLE *PVolumeHandle)
 {
     NTSTATUS Result = STATUS_SUCCESS;
@@ -82,7 +82,7 @@ NTSTATUS FspFsctlOpenVolume(PWSTR VolumePath,
     GlobalDevicePath(DevicePathBuf, sizeof DevicePathBuf, VolumePath);
 
     VolumeHandle = CreateFileW(DevicePathBuf,
-        0, FILE_SHARE_WRITE | FILE_SHARE_WRITE | FILE_SHARE_DELETE, 0, OPEN_EXISTING, 0, 0);
+        0, FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE, 0, OPEN_EXISTING, 0, 0);
     if (INVALID_HANDLE_VALUE == VolumeHandle)
     {
         Result = FspNtStatusFromWin32(GetLastError());
@@ -95,7 +95,7 @@ exit:
     return Result;
 }
 
-NTSTATUS FspFsctlDeleteVolume(HANDLE VolumeHandle)
+FSP_API NTSTATUS FspFsctlDeleteVolume(HANDLE VolumeHandle)
 {
     NTSTATUS Result = STATUS_SUCCESS;
     DWORD Bytes;
@@ -112,7 +112,7 @@ exit:
     return Result;
 }
 
-NTSTATUS FspFsctlTransact(HANDLE VolumeHandle,
+FSP_API NTSTATUS FspFsctlTransact(HANDLE VolumeHandle,
     FSP_TRANSACT_RSP *ResponseBuf, SIZE_T ResponseBufSize,
     FSP_TRANSACT_REQ *RequestBuf, SIZE_T *PRequestBufSize)
 {
diff --git a/src/sys/driver.h b/src/sys/driver.h
index afe3c669..91d50c66 100644
--- a/src/sys/driver.h
+++ b/src/sys/driver.h
@@ -10,8 +10,6 @@
 #include <ntifs.h>
 #include <ntstrsafe.h>
 #include <wdmsec.h>
-
-#define WINFSP_SYS_DRIVER_H_INTERNAL
 #include <winfsp/fsctl.h>
 
 #define DRIVER_NAME                     "WinFsp"
diff --git a/src/sys/fsctl.c b/src/sys/fsctl.c
index ca42ce68..6f67d892 100644
--- a/src/sys/fsctl.c
+++ b/src/sys/fsctl.c
@@ -140,7 +140,7 @@ static NTSTATUS FspFsvrtTransact(
         if (0 == NextResponse)
             break;
 
-        ProcessIrp = FspIoqEndProcessingIrp(&FsvrtDeviceExtension->Ioq, Response->Hint);
+        ProcessIrp = FspIoqEndProcessingIrp(&FsvrtDeviceExtension->Ioq, (UINT_PTR)Response->Hint);
         if (0 == ProcessIrp)
             /* either IRP was canceled or a bogus Hint was provided */
             continue;