diff --git a/build/root/Makefile b/build/root/Makefile
index a392aef3248..cb176b36036 100644
--- a/build/root/Makefile
+++ b/build/root/Makefile
@@ -32,6 +32,9 @@ endif
 # It's necessary to set this because some environments don't link sh -> bash.
 SHELL := /usr/bin/env bash
 
+# Define variables so `make --warn-undefined-variables` works.
+PRINT_HELP ?=
+
 # We don't need make's built-in rules.
 MAKEFLAGS += --no-builtin-rules
 .SUFFIXES:
@@ -56,10 +59,6 @@ $(error Both KUBE_GOFLAGS and GOFLAGS are set. Please use just GOFLAGS)
 endif
 endif
 
-# Extra options for the release or quick-release options:
-KUBE_RELEASE_RUN_TESTS := $(KUBE_RELEASE_RUN_TESTS)
-KUBE_FASTBUILD := $(KUBE_FASTBUILD)
-
 # This controls the verbosity of the build.  Higher numbers mean more output.
 KUBE_VERBOSE ?= 1
 
diff --git a/build/root/Makefile.generated_files b/build/root/Makefile.generated_files
index ac6ac1f991e..daeedd65692 100644
--- a/build/root/Makefile.generated_files
+++ b/build/root/Makefile.generated_files
@@ -32,6 +32,10 @@ endif
 # It's necessary to set this because some environments don't link sh -> bash.
 SHELL := /usr/bin/env bash
 
+# Define variables so `make --warn-undefined-variables` works.
+DBG_CODEGEN ?=
+UPDATE_API_KNOWN_VIOLATIONS ?=
+
 # This rule collects all the generated file sets into a single rule.  Other
 # rules should depend on this to ensure generated files are rebuilt.
 .PHONY: generated_files