diff --git a/Makefile b/Makefile
index 1a0d12c..a4f1c27 100644
--- a/Makefile
+++ b/Makefile
@@ -33,6 +33,12 @@ ifneq ($(ARGS),)
 # then fails with "No rule to make target 'sample'", because make reads every
 # word on the line as something it has been asked to build.
 $(eval $(ARGS):;@:)
+# ...and as PHONY, because some of those words name real directories. `cfg`,
+# `ctrl`, `docs`, `gen` and `init` all exist at this level, and make considers a
+# target that is an existing directory already built — so `make build ctrl` ran
+# the build and then printed "make: 'ctrl' is up to date". The empty rule above
+# is not enough on its own; only .PHONY stops make consulting the filesystem.
+.PHONY: $(ARGS)
 endif
 
 .DEFAULT_GOAL := help