diff --git a/sdk_lib/90_env_keep b/sdk_lib/90_env_keep
index e678b7b1c7..995b9a1a3d 100644
--- a/sdk_lib/90_env_keep
+++ b/sdk_lib/90_env_keep
@@ -5,4 +5,5 @@ Defaults env_keep += "FLATCAR_BUILD_ID COREOS_OFFICIAL \
                       GNUPGHOME GPG_AGENT_INFO SSH_AUTH_SOCK \
                       BOTO_PATH GOOGLE_APPLICATION_CREDENTIALS \
                       USE FEATURES PORTAGE_USERNAME FORCE_STAGES \
+                      SIGNER \
                       all_proxy ftp_proxy http_proxy https_proxy no_proxy"
diff --git a/sdk_lib/sdk_container_common.sh b/sdk_lib/sdk_container_common.sh
index 1e97ef813c..fc88e98d16 100644
--- a/sdk_lib/sdk_container_common.sh
+++ b/sdk_lib/sdk_container_common.sh
@@ -201,6 +201,7 @@ function setup_sdk_env() {
         GIT_COMMITTER_EMAIL GIT_COMMITTER_NAME \
         GIT_PROXY_COMMAND GIT_SSH RSYNC_PROXY \
         GPG_AGENT_INFO FORCE_STAGES \
+        SIGNER \
         all_proxy ftp_proxy http_proxy https_proxy no_proxy; do
 
         if [ -n "${!var:-}" ] ; then