diff --git a/Dockerfile b/Dockerfile
index 7e9386d..79d20f4 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -134,6 +134,7 @@ COPY docker/supervisor/asciinema.conf /etc/supervisor/conf.d/asciinema.conf
 
 # add start script for Clojure app
 
+ENV A2PNG_BIN_PATH "/app/a2png/a2png.sh"
 COPY docker/start.sh /app/start.sh
 RUN chmod a+x /app/start.sh
 
diff --git a/docker/start.sh b/docker/start.sh
index f28182a..c1e684f 100644
--- a/docker/start.sh
+++ b/docker/start.sh
@@ -3,6 +3,5 @@
 export DATABASE_URL=jdbc:${DATABASE_URL}
 export S3_ACCESS_KEY=${AWS_ACCESS_KEY_ID}
 export S3_SECRET_KEY=${AWS_SECRET_ACCESS_KEY}
-export A2PNG_BIN_PATH="/app/a2png/a2png.sh"
 
 exec java -server -jar /app/target/uberjar/asciinema-0.1.0-SNAPSHOT-standalone.jar