diff --git a/Dockerfile b/Dockerfile
index bccade96f6c0aab9b130d89750274fd7c3457d9d..126fd066780f49ab348d29997ef47c066fe44d8c 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -8,7 +8,6 @@ ENV RAILS_ENV=production \
     DISCOURSE_REDIS_HOST=redis \
     DISCOURSE_SERVE_STATIC_ASSETS=true \
     DISCOURSE_VERSION=${DISCOURSE_VERSION} \
-    PNGCRUSH_VERSION=1.8.13 \
     JEMALLOC_NEW=3.6.0 \
     JEMALLOC_STABLE=5.2.1 \
     PG_MAJOR=13 \