diff --git a/Project-Setup.md b/Project-Setup.md
index ec8b69f..2756380 100644
--- a/Project-Setup.md
+++ b/Project-Setup.md
@@ -182,10 +182,13 @@ You may run into parsing errors like `unknown type name 'class'`.
 
 ### Compiler driver
 
-The compiler driver (the first line unless `%compile_commands.json` is used) can usually just be `clang`.
-`clang++` is usually unnecessary, and incorrect if some files are C.
+Just use `clang` as the compiler driver (the first line unless `%compile_commands.json` is used).
 
-Note that `clang a.cc` and `clang++ a.cc` are different, but the difference is only related to linking (what default runtime libraries are passed) and is not relevant for the frontend actions ccls performs.
+* `clang` defaults to GCCMode (gcc). It correctly treats `.c` files as C and `.cpp` files as C++.
+* `clang++` defaults to GXXMode (g++). It treats a `.c` file as C++ and issues a warning.
+
+`clang a.cc` and `clang++ a.cc` are different, but the difference is only related to linking (what default runtime libraries are passed) and is not relevant for the frontend actions ccls performs.
+So for ccls use cases, just stick with `clang`.
 
 ## `.ccls` examples