diff --git a/sdk_lib/enter_chroot.sh b/sdk_lib/enter_chroot.sh
index 3e4d980978..ca2725f13b 100755
--- a/sdk_lib/enter_chroot.sh
+++ b/sdk_lib/enter_chroot.sh
@@ -586,8 +586,11 @@ CHROOT_PASSTHRU=(
   "SSH_AUTH_SOCK=${SSH_AUTH_SOCK}"
 )
 
+# Some vars we want to keep.
+KEEP_VARS="USE GCC_GITHASH"
 # Pass proxy variables into the environment.
-for type in http_proxy ftp_proxy all_proxy GIT_PROXY_COMMAND GIT_SSH; do
+PROXY_VARS="http_proxy ftp_proxy all_proxy GIT_PROXY_COMMAND GIT_SSH"
+for type in ${KEEP_VARS} ${PROXY_VARS}; do
   if [ -n "${!type}" ]; then
     CHROOT_PASSTHRU+=( "${type}=${!type}" )
   fi
diff --git a/sdk_lib/make_chroot.sh b/sdk_lib/make_chroot.sh
index a02ffd1f0d..4d459d211a 100755
--- a/sdk_lib/make_chroot.sh
+++ b/sdk_lib/make_chroot.sh
@@ -16,6 +16,11 @@ ENTER_CHROOT=$(readlink -f $(dirname "$0")/enter_chroot.sh)
 
 enable_strict_sudo
 
+if [ -n "${USE}" ]; then
+  echo "$SCRIPT_NAME: Building with a non-empty USE: ${USE}"
+  echo "This modifies the expected behaviour and can fail."
+fi
+
 # Check if the host machine architecture is supported.
 ARCHITECTURE="$(uname -m)"
 if [[ "$ARCHITECTURE" != "x86_64" ]]; then
@@ -457,7 +462,7 @@ fi
 
 # As a final pass, build all desired cross-toolchains.
 info "Updating toolchains"
-enter_chroot sudo "${CHROOT_TRUNK}/chromite/bin/cros_setup_toolchains" \
+enter_chroot sudo -E "${CHROOT_TRUNK}/chromite/bin/cros_setup_toolchains" \
     "${TOOLCHAIN_ARGS[@]}"
 
 command_completed