diff --git a/.docker/Dockerfile.php b/.docker/Dockerfile.php
index 376baa4..0e3ab81 100644
--- a/.docker/Dockerfile.php
+++ b/.docker/Dockerfile.php
@@ -8,7 +8,13 @@
 FROM ${CLI_IMAGE} as cli
 FROM govcms/php:${GOVCMS_IMAGE_VERSION}
 
+ARG LAGOON_PROJECT
+ARG LAGOON_ENVIRONMENT
+
 # Clean up base image so as not to conflict with any changes.
 RUN rm -rf /app
 
 COPY --from=cli /app /app
+
+# Define HTTPAV identifier.
+ENV HTTPAV_IDENTIFIER=${LAGOON_PROJECT}-${LAGOON_ENVIRONMENT}