diff --git a/containers/xos/Dockerfile.devel b/containers/xos/Dockerfile.devel
index e6fd066..6739f62 100644
--- a/containers/xos/Dockerfile.devel
+++ b/containers/xos/Dockerfile.devel
@@ -101,7 +101,7 @@
 ENV OPENSSL openssl
 ENV PKCS11TOOL pkcs11-tool
 ENV GREP grep
-ENV KEY_CONFIG '$EASY_RSA/whichopensslcnf $EASY_RSA'
+ENV KEY_CONFIG `$EASY_RSA/whichopensslcnf $EASY_RSA`
 ENV KEY_DIR $EASY_RSA/keys
 ENV PKCS11_MODULE_PATH dummy
 ENV PKCS11_PIN dummy