diff --git a/build.cmd b/build.cmd
index 6584273d8..5ce5f15b8 100644
--- a/build.cmd
+++ b/build.cmd
@@ -1,4 +1,5 @@
 @ECHO OFF
 setlocal
 set PATH=%PATH%;%ProgramFiles(x86)%\MSBuild\14.0\Bin;%ProgramFiles(x86)%\MSBuild\12.0\Bin;%WINDIR%\Microsoft.NET\Framework\v4.0.30319
+rd /s /q build
 MSBuild.exe msbuild\WebSharper.proj /verbosity:minimal /p:Arguments="%*"