diff --git a/Dockerfile b/Dockerfile
index 4b3fbe66..5da4ad04 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -10,11 +10,16 @@ WORKDIR /src
 RUN curl https://sh.rustup.rs -sSf | sh -s -- -y --profile minimal
 ENV PATH="/root/.cargo/bin:${PATH}"
 
+# Needed to build rust things for matrix-sdk-crypto-nodejs
+# See https://github.com/matrix-org/matrix-rust-sdk-bindings/blob/main/crates/matrix-sdk-crypto-nodejs/release/Dockerfile.linux#L5-L6
+RUN apt-get update && apt-get install -y build-essential cmake
+
 # Workaround: Need to install esbuild manually https://github.com/evanw/esbuild/issues/462#issuecomment-771328459
 RUN yarn --ignore-scripts
 RUN node node_modules/esbuild/install.js
 RUN yarn build --pure-lockfile
 
+
 # Stage 1: The actual container
 FROM node:16-slim
 
@@ -23,9 +28,13 @@ COPY --from=builder /src/public/ /bin/matrix-hookshot/public/
 COPY --from=builder /src/package.json /bin/matrix-hookshot/
 COPY --from=builder /src/yarn.lock /bin/matrix-hookshot/
 WORKDIR /bin/matrix-hookshot
+
 # --ignore-scripts so we don't try to build
 RUN yarn --ignore-scripts --production --pure-lockfile && yarn cache clean
 
+# Copy rust bindings for crypto, since we built them in the previous step.
+COPY --from=builder /src/node_modules/@turt2live/matrix-sdk-crypto-nodejs /bin/matrix-hookshot/node_modules/@turt2live/matrix-sdk-crypto-nodejs
+
 VOLUME /data
 EXPOSE 9993
 EXPOSE 7775
diff --git a/changelog.d/339.bugfix b/changelog.d/339.bugfix
new file mode 100644
index 00000000..8e70f053
--- /dev/null
+++ b/changelog.d/339.bugfix
@@ -0,0 +1 @@
+Docker images can now be built cross-platform. Thanks @ptman for getting arm64 builds going!
diff --git a/scripts/build-app.sh b/scripts/build-app.sh
index 8dc3d158..e60096f1 100755
--- a/scripts/build-app.sh
+++ b/scripts/build-app.sh
@@ -1,8 +1,14 @@
-#!/bin/sh
+#!/bin/bash
 
 # exit when any command fails
 set -e
 
+# Workaround for non-x64 / ia32 targets
+pushd node_modules/@turt2live/matrix-sdk-crypto-nodejs
+echo "Checking matrix-sdk-crypto-nodejs bindings (and building if required)"
+node check-exists.js
+popd
+
 echo "Building Rust layer"
 yarn run build:app:rs
 echo "Running rust-typescript definitions fix"