diff --git a/.dockerignore b/.dockerignore
index e3ba81e97..b6764a50f 100644
--- a/.dockerignore
+++ b/.dockerignore
@@ -15,7 +15,8 @@ TODO.md
 # Sibling projects / test harness - not part of the webmail image
 examples/
 # Unit tests: `next build` type-checks every .ts file, and some tests import
-# routes the Dockerfile deletes (app/api/dev-jmap)
+# routes the Dockerfile deletes (app/api/dev-jmap). The Dockerfile deletes the
+# tests as well, since a remote Git context skips this file.
 **/__tests__
 **/*.test.ts
 **/*.test.tsx
diff --git a/Dockerfile b/Dockerfile
index b36abc8fd..c9efc1cfa 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -23,7 +23,14 @@ ARG GIT_COMMIT=unknown
 ENV GIT_COMMIT=$GIT_COMMIT
 # The mock JMAP server (DEV_MOCK_JMAP) accepts any password and is for
 # `npm run dev` only; images ship without it.
-RUN rm -rf "app/api/dev-jmap" && npx next build --webpack
+# `next build` type-checks every .ts file, and some unit tests import the
+# deleted route, so the tests go too. .dockerignore already drops them from a
+# local context, but a remote Git context never applies .dockerignore (#1118).
+RUN rm -rf "app/api/dev-jmap" && \
+    find . -path ./node_modules -prune -o \
+      \( -name __tests__ -o -name "*.test.ts" -o -name "*.test.tsx" \) \
+      -prune -exec rm -rf {} \; && \
+    npx next build --webpack
 
 FROM node:24-alpine AS runner