diff --git a/Build.md b/Build.md
index 008769f..77f6cbe 100644
--- a/Build.md
+++ b/Build.md
@@ -203,13 +203,14 @@ To build using MacPorts Clang add CMake flags
 -DCMAKE_PREFIX_PATH=/opt/local/libexec/llvm-6.0
 ```
 
-With clang < 8, to make header completion work, use a [shell script wrapper](Install#shell-script-wrapper):
+See https://github.com/MaskRay/ccls/issues/512 , use a [shell script wrapper](Install#shell-script-wrapper):
+
 ```sh
 #!/bin/sh
-exec /path/to/ccls/Release/ccls -init='{"clang":{"extraArgs":["-isystem", "/Library/Developer/CommandLineTools/usr/include/c++/v1"]}}' "$@"
+exec /path/to/ccls/Release/ccls -init='{"clang":{"extraArgs":["-isystem", "/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include"]}}' "$@"
 ```
 
-See https://github.com/MaskRay/ccls/issues/191#issuecomment-453809905 for details.
+With clang < 8, `"-isystem", "/Library/Developer/CommandLineTools/usr/include/c++/v1"` is also needed (https://github.com/MaskRay/ccls/issues/191#issuecomment-453809905)
 
 ### FreeBSD