diff --git a/Dockerfile b/Dockerfile
index 51bcd9c..cb8e0d4 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -15,6 +15,7 @@ WORKDIR /app
 # intentionally here only for temporary cache-busting test
 # COPY ./client ./client
 
+RUN apt-get update
 RUN apt-get install libsdl2-dev
 
 COPY ./pico8 ./pico8