diff --git a/bin/cli.rb b/bin/cli.rb
index f63cc7f8..f834a946 100644
--- a/bin/cli.rb
+++ b/bin/cli.rb
@@ -304,6 +304,9 @@ def upgrade(path)
 
       • `--test-case` and its inverse `--exclude-test-case` set test case name 
       matchers to run only a subset of the unit test suite. See docs for full details.
+
+      • The simple `--log` flag and more configurable `--logfile <filepath>` are 
+      mutually exclusive. It is valid to use one or the other but not both.
       LONGDESC
     ) )
     def build(*tasks)