diff --git a/Dockerfile b/Dockerfile
index c3bf67e..c25d6ab 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,13 +1,14 @@
 # == base ======================
 FROM buildpack-deps:bookworm AS base
 ENV CACHEBUST=2024-09-17
-RUN useradd -m -d /project -u 8000 observable-builder && apt update
+RUN useradd -m -u 8000 observable-builder && mkdir /project && \
+    chown 8000:8000 /project && apt update
 
 ENV RUSTUP_HOME=/usr/local/rustup \
     CARGO_HOME=/usr/local/cargo \
     RUST_VERSION=1.81.0 \
-    VIRTUAL_ENV=/project/.local/python-venv
-ENV PATH=/usr/local/cargo/bin:$VIRTUAL_ENV/bin:/project/.local/bin:$PATH
+    VIRTUAL_ENV=/home/observable-builder/.local/python-venv
+ENV PATH=/usr/local/cargo/bin:$VIRTUAL_ENV/bin:/home/observable-builder/.local/bin:$PATH
 
 # == node ======================
 FROM base AS node
@@ -33,10 +34,7 @@ RUN --mount=type=cache,target=/var/cache/apt,id=framework-runtime-python \
       python3-dev \
       python3-venv \
       pipx
-
-FROM python AS python-poetry
 USER 8000
-WORKDIR /project
 RUN pipx install poetry \
     && python3 -m venv $VIRTUAL_ENV
 
@@ -126,7 +124,6 @@ FROM base AS runtime
 COPY --from=general-cli . .
 COPY --from=node . .
 COPY --from=python . .
-COPY --from=python-poetry . .
 COPY --from=r . .
 COPY --from=duckdb . .
 COPY --from=rust . .
diff --git a/package.json b/package.json
index ffd2c14..8371127 100644
--- a/package.json
+++ b/package.json
@@ -16,10 +16,8 @@
     "dockerode": "^4.0.2",
     "glob": "^10.3.12",
     "semver": "^7.6.0",
+    "tar-fs": "^3.0.6",
     "tsx": "^4.7.1",
     "typescript": "^5.4.3"
-  },
-  "dependencies": {
-    "tar-fs": "^3.0.6"
   }
 }
diff --git a/tests/dataloader-languages.test.ts b/tests/dataloader-languages.test.ts
index a7de187..80785fa 100644
--- a/tests/dataloader-languages.test.ts
+++ b/tests/dataloader-languages.test.ts
@@ -83,7 +83,7 @@ describe("Dataloader languages", () => {
         ],
         {
           workingDir: "/project/poetry-test",
-          mounts: [{ host: "./tests/fixtures/poetry-test", container: "/project/poetry-test" }],
+          hostContainerDirs: [{ host: "./tests/fixtures/poetry-test", container: "/project/poetry-test" }],
         },
       );
     });
diff --git a/tests/index.ts b/tests/index.ts
index eef91f7..cbc268d 100644
--- a/tests/index.ts
+++ b/tests/index.ts
@@ -1,12 +1,9 @@
 import { test, before } from "node:test";
-import { resolve } from "node:path";
 import assert from "node:assert";
 import Dockerode from "dockerode";
 import { Stream } from "node:stream";
 import semverSatisfies from "semver/functions/satisfies";
-import { basename } from "node:path";
 import tar from "tar-fs";
-import { readFileSync } from "node:fs";
 
 export const IMAGE_TAG = "observablehq/framework-runtime:test";
 
@@ -91,9 +88,9 @@ before(ensureDocker);
 
 function copyFilesToContainer(
   dockerContainer: Dockerode.Container,
-  files: { host: string; container: string }[],
+  directories: { host: string; container: string }[],
 ) {
-  for (const { host, container } of files) {
+  for (const { host, container } of directories) {
     const tarStream = tar.pack(host);
     dockerContainer.putArchive(tarStream, { path: container });
   }
@@ -102,10 +99,10 @@ function copyFilesToContainer(
 export async function runCommandInContainer(
   command: string[],
   {
-    mounts = [],
+    hostContainerDirs = [],
     workingDir = "/project",
   }: {
-    mounts?: { host: string; container: string}[];
+    hostContainerDirs?: { host: string; container: string}[];
     workingDir?: string;
   } = {},
 ): Promise<{ stdout: string; stderr: string }> {
@@ -116,7 +113,7 @@ export async function runCommandInContainer(
     Cmd: command,
   });
 
-  copyFilesToContainer(container, mounts);
+  copyFilesToContainer(container, hostContainerDirs);
 
   const stdout = new StringStream();
   const stderr = new StringStream();