diff --git a/configure b/configure
index 2a18beeb8c9..84ed6fa8954 100755
--- a/configure
+++ b/configure
@@ -716,18 +716,6 @@ if [ -n "$CFG_ENABLE_DEBUG_JEMALLOC" ]; then putvar CFG_ENABLE_DEBUG_JEMALLOC; f
 
 if [ -n "$CFG_ENABLE_ORBIT" ]; then putvar CFG_ENABLE_ORBIT; fi
 
-# A magic value that allows the compiler to use unstable features
-# during the bootstrap even when doing so would normally be an error
-# because of feature staging or because the build turns on
-# warnings-as-errors and unstable features default to warnings.  The
-# build has to match this key in an env var. Meant to be a mild
-# deterrent from users just turning on unstable features on the stable
-# channel.
-# Basing CFG_BOOTSTRAP_KEY on CFG_BOOTSTRAP_KEY lets it get picked up
-# during a Makefile reconfig.
-CFG_BOOTSTRAP_KEY="${CFG_BOOTSTRAP_KEY-`date +%H:%M:%S`}"
-putvar CFG_BOOTSTRAP_KEY
-
 step_msg "looking for build programs"
 
 probe_need CFG_CURLORWGET  curl wget
diff --git a/mk/main.mk b/mk/main.mk
index a32658ddcef..9b8080f9661 100644
--- a/mk/main.mk
+++ b/mk/main.mk
@@ -24,6 +24,17 @@ CFG_PRERELEASE_VERSION=.1
 # versions in the same place
 CFG_FILENAME_EXTRA=$(shell printf '%s' $(CFG_RELEASE)$(CFG_EXTRA_FILENAME) | $(CFG_HASH_COMMAND))
 
+# A magic value that allows the compiler to use unstable features during the
+# bootstrap even when doing so would normally be an error because of feature
+# staging or because the build turns on warnings-as-errors and unstable features
+# default to warnings. The build has to match this key in an env var.
+#
+# This value is keyed off the release to ensure that all compilers for one
+# particular release have the same bootstrap key. Note that this is
+# intentionally not "secure" by any definition, this is largely just a deterrent
+# from users enabling unstable features on the stable compiler.
+CFG_BOOTSTRAP_KEY=$(CFG_FILENAME_EXTRA)
+
 ifeq ($(CFG_RELEASE_CHANNEL),stable)
 # This is the normal semver version string, e.g. "0.12.0", "0.12.0-nightly"
 CFG_RELEASE=$(CFG_RELEASE_NUM)