diff --git a/tools/build.bat b/tools/build.bat
index 22d6a496..0b827522 100755
--- a/tools/build.bat
+++ b/tools/build.bat
@@ -2,61 +2,78 @@
 
 setlocal
 
-set Configuration=Release
 set MsiName="WinFsp - Windows File System Proxy"
 set CrossCert="%~dp0DigiCert High Assurance EV Root CA.crt"
 set Issuer="DigiCert"
 set Subject="Navimatics Corporation"
 
+set Configuration=Release
+set SignedPackage=
+
 if not X%1==X set Configuration=%1
+if not X%2==X set SignedPackage=%2
 
 call "%VS140COMNTOOLS%\..\..\VC\vcvarsall.bat" x64
 
+if not X%SignedPackage%==X (
+    if not exist "%~dp0..\build\VStudio\build\%Configuration%\winfsp-*.msi" (echo previous build not found >&2 & exit /b 1)
+    if not exist "%SignedPackage%" (echo signed package not found >&2 & exit /b 1)
+    del "%~dp0..\build\VStudio\build\%Configuration%\winfsp-*.msi"
+    for /R "%SignedPackage%" %%f in (*.sys) do (
+        copy "%%f" "%~dp0..\build\VStudio\build\%Configuration%" >nul
+    )
+)
+
 cd %~dp0..\build\VStudio
-if exist build\ del /s/q build >nul
-
-devenv winfsp.sln /build "%Configuration%|x64"
-if errorlevel 1 goto fail
-devenv winfsp.sln /build "%Configuration%|x86"
-if errorlevel 1 goto fail
-
 set signfail=0
-for %%f in (build\%Configuration%\winfsp-x64.sys build\%Configuration%\winfsp-x86.sys) do (
-	signtool sign /ac %CrossCert% /i %Issuer% /n %Subject% /fd sha1 /t http://timestamp.digicert.com %%f
-	if errorlevel 1 set /a signfail=signfail+1
-	signtool sign /as /ac %CrossCert% /i %Issuer% /n %Subject% /fd sha256 /tr http://timestamp.digicert.com /td sha256 %%f
-	if errorlevel 1 set /a signfail=signfail+1
-)
 
-pushd build\%Configuration%
-for %%a in (x64 x86) do (
-	echo .OPTION EXPLICIT >driver-%%a.ddf
-	echo .Set CabinetFileCountThreshold=0 >>driver-%%a.ddf
-	echo .Set FolderFileCountThreshold=0 >>driver-%%a.ddf
-	echo .Set FolderSizeThreshold=0 >>driver-%%a.ddf
-	echo .Set MaxCabinetSize=0 >>driver-%%a.ddf
-	echo .Set MaxDiskFileCount=0 >>driver-%%a.ddf
-	echo .Set MaxDiskSize=0 >>driver-%%a.ddf
-	echo .Set CompressionType=MSZIP >>driver-%%a.ddf
-	echo .Set Cabinet=on >>driver-%%a.ddf
-	echo .Set Compress=on >>driver-%%a.ddf
-	echo .Set CabinetNameTemplate=driver-%%a.cab >>driver-%%a.ddf
-	echo .Set DiskDirectory1=. >>driver-%%a.ddf
-	echo .Set DestinationDir=winfsp >>driver-%%a.ddf
-	echo driver-%%a.inf >>driver-%%a.ddf
-	echo winfsp-%%a.sys >>driver-%%a.ddf
-	makecab /F driver-%%a.ddf
+if X%SignedPackage%==X (
+    if exist build\ for /R build\ %%d in (%Configuration%) do (
+        if exist "%%d" rmdir /s/q "%%d"
+    )
+
+    devenv winfsp.sln /build "%Configuration%|x64"
+    if errorlevel 1 goto fail
+    devenv winfsp.sln /build "%Configuration%|x86"
+    if errorlevel 1 goto fail
+
+    for %%f in (build\%Configuration%\winfsp-x64.sys build\%Configuration%\winfsp-x86.sys) do (
+        signtool sign /ac %CrossCert% /i %Issuer% /n %Subject% /fd sha1 /t http://timestamp.digicert.com %%f
+        if errorlevel 1 set /a signfail=signfail+1
+        signtool sign /as /ac %CrossCert% /i %Issuer% /n %Subject% /fd sha256 /tr http://timestamp.digicert.com /td sha256 %%f
+        if errorlevel 1 set /a signfail=signfail+1
+    )
+
+    pushd build\%Configuration%
+    for %%a in (x64 x86) do (
+        echo .OPTION EXPLICIT >driver-%%a.ddf
+        echo .Set CabinetFileCountThreshold=0 >>driver-%%a.ddf
+        echo .Set FolderFileCountThreshold=0 >>driver-%%a.ddf
+        echo .Set FolderSizeThreshold=0 >>driver-%%a.ddf
+        echo .Set MaxCabinetSize=0 >>driver-%%a.ddf
+        echo .Set MaxDiskFileCount=0 >>driver-%%a.ddf
+        echo .Set MaxDiskSize=0 >>driver-%%a.ddf
+        echo .Set CompressionType=MSZIP >>driver-%%a.ddf
+        echo .Set Cabinet=on >>driver-%%a.ddf
+        echo .Set Compress=on >>driver-%%a.ddf
+        echo .Set CabinetNameTemplate=driver-%%a.cab >>driver-%%a.ddf
+        echo .Set DiskDirectory1=. >>driver-%%a.ddf
+        echo .Set DestinationDir=winfsp >>driver-%%a.ddf
+        echo driver-%%a.inf >>driver-%%a.ddf
+        echo winfsp-%%a.sys >>driver-%%a.ddf
+        makecab /F driver-%%a.ddf
+    )
+    popd
 )
-popd
 
 devenv winfsp.sln /build "Installer.%Configuration%|x86"
 if errorlevel 1 goto fail
 
 for %%f in (build\%Configuration%\winfsp-*.msi) do (
-	signtool sign /ac %CrossCert% /i %Issuer% /n %Subject% /fd sha1 /t http://timestamp.digicert.com /d %MsiName% %%f
-	if errorlevel 1 set /a signfail=signfail+1
-	REM signtool sign /ac %CrossCert% /i %Issuer% /n %Subject% /fd sha256 /tr http://timestamp.digicert.com /td sha256 /d %MsiName% %%f
-	REM if errorlevel 1 set /a signfail=signfail+1
+    signtool sign /ac %CrossCert% /i %Issuer% /n %Subject% /fd sha1 /t http://timestamp.digicert.com /d %MsiName% %%f
+    if errorlevel 1 set /a signfail=signfail+1
+    REM signtool sign /ac %CrossCert% /i %Issuer% /n %Subject% /fd sha256 /tr http://timestamp.digicert.com /td sha256 /d %MsiName% %%f
+    REM if errorlevel 1 set /a signfail=signfail+1
 )
 
 if not %signfail%==0 echo SIGNING FAILED! The product has been successfully built, but not signed.