diff --git a/online_demo/README.md b/online_demo/README.md
index fb6c8977..e45b6be4 100644
--- a/online_demo/README.md
+++ b/online_demo/README.md
@@ -57,11 +57,8 @@ git submodule update --init
 mkdir build
 cp cmake/config.cmake build/
 cd build
-#[
-#edit config.cmake to change
-# 32 line: USE_CUDA OFF -> USE_CUDA ON
-#104 line: USE_LLVM OFF -> USE_LLVM ON
-#]
+sed -i "s/USE_CUDA OFF/USE_CUDA ON/g" ./config.cmake
+sed -i "s/USE_LLVM OFF/USE_LLVM ON/g" ./config.cmake
 cmake ..
 make -j4
 cd ..
@@ -120,4 +117,4 @@ For any problems, contact:
 
 Ji Lin, jilin@mit.edu
 
-Yaoyao Ding, yyding@mit.edu
\ No newline at end of file
+Yaoyao Ding, yyding@mit.edu