diff --git a/pep-0517.txt b/pep-0517.txt
index ea0cc8e1b..a60bb3992 100644
--- a/pep-0517.txt
+++ b/pep-0517.txt
@@ -474,7 +474,8 @@ following criteria:
   work as a mechanism for running the flit command-line tool::
 
     import subprocess
-    subprocess.check_call(["flit", ...])
+    import shutil
+    subprocess.check_call([shutil.which("flit"), ...])
 
 A build backend MUST be prepared to function in any environment which
 meets the above criteria. In particular, it MUST NOT assume that it