diff --git a/ci/stack_env.sh b/ci/stack_env.sh
index 311356f128e105c917d29f174b3f17f8f04a4d63..44ef1b2abd04ae63a92f3fd07244cd0592194cc1 100644
--- a/ci/stack_env.sh
+++ b/ci/stack_env.sh
@@ -29,6 +29,13 @@ else
     export acc_type="none"
 fi
 
+set +u
+if [ "x$GPG_KEY_ID" == "x" ]
+then
+    export GPG_KEY_ID=$(gpg --show-keys $GPG_PRIVATE_KEY 2> /dev/null | head -n 2 | tail -1)
+fi
+set -u
+
 echo "STACK_CONFIG_PATH: ${STACK_CONFIG_PATH}"
 echo "STACK_CONFIG: ${STACK_CONFIG}"
 echo "SPACK_VERSION: ${SPACK_VERSION}"