diff --git a/docs/Build.md b/docs/Build.md
index 3d80215e50..87575f9e23 100644
--- a/docs/Build.md
+++ b/docs/Build.md
@@ -60,6 +60,7 @@ Hit "Configure Project", then wait for CMake to finish configuring (may take a w
 >  - It's recommended to install **[Ninja](https://ninja-build.org/)**
 >  - You must load **Visual C++ development environment**, this can be done by running our convenience script:
 >    - `tools/windows/load-msvc-env.ps1`
+>  - You need to add the environment variable `CL` with the `/FS` flag (`set CL=/FS`)  if you're using ccache to speed up build process
 
 Availables `<GENERATOR>`:
 - MSYS2: `MSYS Makefiles`