diff --git a/.changeset/six-ladybugs-notice.md b/.changeset/six-ladybugs-notice.md
new file mode 100644
index 000000000..65ef7b0eb
--- /dev/null
+++ b/.changeset/six-ladybugs-notice.md
@@ -0,0 +1,12 @@
+---
+'skuba': patch
+---
+
+template/\*-rest-api: Avoid alternative syntax for ENV instructions
+
+Omitting the `=` symbol in ENV instructions [is discouraged and may be disallowed in future](https://docs.docker.com/engine/reference/builder/#env).
+
+```diff
+- ENV NODE_ENV production
++ ENV NODE_ENV=production
+```
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 307f58516..98a96f11c 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -113,7 +113,7 @@
   + FROM gcr.io/distroless/nodejs:16 AS runtime
 
   + # https://nodejs.org/api/cli.html#cli_node_options_options
-  + ENV NODE_OPTIONS --enable-source-maps
+  + ENV NODE_OPTIONS=--enable-source-maps
   ```
 
   For a Serverless Lambda application, update your `serverless.yml`:
diff --git a/template/express-rest-api/Dockerfile b/template/express-rest-api/Dockerfile
index 131346e64..a29bc103a 100644
--- a/template/express-rest-api/Dockerfile
+++ b/template/express-rest-api/Dockerfile
@@ -25,13 +25,13 @@ COPY --from=build /workdir/lib lib
 
 COPY --from=deps /workdir/node_modules node_modules
 
-ENV NODE_ENV production
+ENV NODE_ENV=production
 
 # https://nodejs.org/api/cli.html#cli_node_options_options
-ENV NODE_OPTIONS --enable-source-maps
+ENV NODE_OPTIONS=--enable-source-maps
 
 ARG PORT=8001
-ENV PORT ${PORT}
+ENV PORT=${PORT}
 EXPOSE ${PORT}
 
 CMD ["lib/listen.js"]
diff --git a/template/koa-rest-api/Dockerfile b/template/koa-rest-api/Dockerfile
index ba01e4ec0..85d41ee48 100644
--- a/template/koa-rest-api/Dockerfile
+++ b/template/koa-rest-api/Dockerfile
@@ -25,13 +25,13 @@ COPY --from=build /workdir/lib lib
 
 COPY --from=deps /workdir/node_modules node_modules
 
-ENV NODE_ENV production
+ENV NODE_ENV=production
 
 # https://nodejs.org/api/cli.html#cli_node_options_options
-ENV NODE_OPTIONS --enable-source-maps
+ENV NODE_OPTIONS=--enable-source-maps
 
 ARG PORT=8001
-ENV PORT ${PORT}
+ENV PORT=${PORT}
 EXPOSE ${PORT}
 
 CMD ["--require", "./lib/tracing.js", "./lib/listen.js"]