diff --git a/bin/build_wasm.bat b/bin/build_wasm.bat
index dc32e9ba..f0367f44 100644
--- a/bin/build_wasm.bat
+++ b/bin/build_wasm.bat
@@ -1,6 +1,34 @@
-mkdir ..\wasm
-cd ..\wasm
-call emcc ..\BeefRT\rt\Chars.cpp ..\BeefRT\rt\Math.cpp ..\BeefRT\rt\Object.cpp ..\BeefRT\rt\Thread.cpp ..\BeefRT\rt\Internal.cpp ..\BeefySysLib\platform\wasm\WasmCommon.cpp ..\BeefySysLib\Common.cpp ..\BeefySysLib\util\String.cpp ..\BeefySysLib\util\UTF8.cpp ..\BeefySysLib\third_party\utf8proc\utf8proc.c -I..\ -I..\BeefySysLib -I..\BeefySysLib\platform\wasm -g -DBF_DISABLE_FFI -c -s WASM=1 -s USE_PTHREADS=1
+PUSHD %~dp0..\
+
+mkdir wasm
+cd wasm
+@IF %ERRORLEVEL% NEQ 0 GOTO HADERROR
+
+@IF NOT EXIST ..\BeefRT\rt\Chars.cpp GOTO SKIPCOPY
+mkdir src
+mkdir src\rt
+copy ..\BeefRT\rt\* src\rt\
+mkdir src\BeefySysLib
+copy ..\BeefySysLib\*.h src\BeefySysLib\
+copy ..\BeefySysLib\Common.cpp src\BeefySysLib\
+mkdir src\BeefySysLib\platform
+copy ..\BeefySysLib\platform\* src\BeefySysLib\platform\
+mkdir src\BeefySysLib\platform\posix
+copy ..\BeefySysLib\platform\posix\* src\BeefySysLib\platform\posix\
+mkdir src\BeefySysLib\platform\wasm
+copy ..\BeefySysLib\platform\wasm\* src\BeefySysLib\platform\wasm\
+mkdir src\BeefySysLib\util
+copy ..\BeefySysLib\util\* src\BeefySysLib\util\
+mkdir src\BeefySysLib\third_party
+mkdir src\BeefySysLib\third_party\utf8proc
+copy ..\BeefySysLib\third_party\utf8proc\* src\BeefySysLib\third_party\utf8proc
+mkdir src\BeefySysLib\third_party\stb
+copy ..\BeefySysLib\third_party\stb\* src\BeefySysLib\third_party\stb
+:SKIPCOPY
+
+@IF "%1" EQU "setup" GOTO SUCCESS
+
+call emcc src\rt\Chars.cpp src\rt\Math.cpp src\rt\Object.cpp src\rt\Thread.cpp src\rt\Internal.cpp src\BeefySysLib\platform\wasm\WasmCommon.cpp src\BeefySysLib\Common.cpp src\BeefySysLib\util\String.cpp src\BeefySysLib\util\UTF8.cpp src\BeefySysLib\third_party\utf8proc\utf8proc.c -Isrc\ -Isrc\BeefySysLib -Isrc\BeefySysLib\platform\wasm -g -DBF_DISABLE_FFI -c -s WASM=1 -s USE_PTHREADS=1
 @IF %ERRORLEVEL% NEQ 0 GOTO HADERROR
 call emar r ..\IDE\dist\Beef042RT32_wasm.a Common.o Internal.o Chars.o Math.o Object.o String.o Thread.o UTF8.o utf8proc.o WasmCommon.o
 @IF %ERRORLEVEL% NEQ 0 GOTO HADERROR