diff --git a/docker/dev/Dockerfile b/docker/dev/Dockerfile
index 48bf41b..abe394b 100644
--- a/docker/dev/Dockerfile
+++ b/docker/dev/Dockerfile
@@ -1,5 +1,5 @@
 # Build 
-FROM ekidd/rust-musl-builder:1.42.0-openssl11 as rust
+FROM ekidd/rust-musl-builder:1.44.0 as rust
 
 # Cache deps
 WORKDIR /app
@@ -17,7 +17,7 @@ COPY src ./src/
 # Build for release
 RUN cargo build --frozen --release
 
-FROM alpine:3.10
+FROM alpine:3.11
 
 # Copy resources
 COPY --from=rust /app/server/target/x86_64-unknown-linux-musl/release/pict-rs /app/pict-rs
diff --git a/src/config.rs b/src/config.rs
index 8ea873a..40a56f9 100644
--- a/src/config.rs
+++ b/src/config.rs
@@ -22,13 +22,14 @@ pub(crate) struct Config {
         short,
         long,
         env = "PICTRS_FORMAT",
-        help = "An image format to convert all uploaded files into, supports 'jpg' and 'png'"
+        help = "An optional image format to convert all uploaded files into, supports 'jpg' and 'png'"
     )]
     format: Option<Format>,
 
     #[structopt(
         short,
         long,
+        env = "PICTRS_FILTER_WHITELIST",
         help = "An optional list of filters to whitelist, supports 'identity', 'thumbnail', and 'blur'"
     )]
     whitelist: Option<Vec<String>>,