doc: Clarify default value of sourceRoot

1 files changed, 2 insertions, 0 deletions

diff --git a/doc/stdenv/stdenv.chapter.md b/doc/stdenv/stdenv.chapter.md
index fa61973263aed..93351ce1bdb3c 100644
--- a/doc/stdenv/stdenv.chapter.md
+++ b/doc/stdenv/stdenv.chapter.md
@@ -452,6 +452,8 @@ The list of source files or directories to be unpacked or copied. One of these m
 
 After running `unpackPhase`, the generic builder changes the current directory to the directory created by unpacking the sources. If there are multiple source directories, you should set `sourceRoot` to the name of the intended directory. Set `sourceRoot = ".";` if you use `srcs` and control the unpack phase yourself.
 
+By default the `sourceRoot` is set to `"source"`. If you want to point to a sub-directory inside your project, you therefore need to set `sourceRoot = "source/my-sub-directory"`.
+
 ##### `setSourceRoot` {#var-stdenv-setSourceRoot}
 
 Alternatively to setting `sourceRoot`, you can set `setSourceRoot` to a shell command to be evaluated by the unpack phase after the sources have been unpacked. This command must set `sourceRoot`.