diff --git a/Documentation/CodingGuidelines b/Documentation/CodingGuidelines
index cfe378590..45577117c 100644
--- a/Documentation/CodingGuidelines
+++ b/Documentation/CodingGuidelines
@@ -46,6 +46,11 @@ For shell scripts specifically (not exhaustive):
    properly nests.  It should have been the way Bourne spelled
    it from day one, but unfortunately isn't.
 
+ - If you want to find out if a command is available on the user's
+   $PATH, you should use 'type <command>', instead of 'which <command>'.
+   The output of 'which' is not machine parseable and its exit code
+   is not reliable across platforms.
+
  - We use POSIX compliant parameter substitutions and avoid bashisms;
    namely: