diff --git a/helpers/repro-run.ts b/helpers/repro-run.ts
index 797a732..9f60f38 100644
--- a/helpers/repro-run.ts
+++ b/helpers/repro-run.ts
@@ -1,3 +1,5 @@
+import { chmod, mkdir, readFile, writeFile } from "node:fs/promises";
+import { join } from "node:path";
 import { Writable } from "node:stream";
 import { execFile } from "./better-api.js";
 
@@ -21,3 +23,29 @@ export async function reproRun(opts: {
   run.child.stderr?.pipe(process.stderr);
   await run;
 }
+
+export async function buildRepro<T>(
+  cacheName: string,
+  cacheKey: string,
+  buildScript: string,
+  run: (cwd: string) => Promise<void>,
+  getArtifacts: (cwd: string) => T
+): Promise<T> {
+  const dir = join("cache", cacheName);
+  await mkdir(dir, { recursive: true });
+  const cacheKeyFile = join(dir, "version");
+  const output = getArtifacts(dir);
+  try {
+    if ((await readFile(cacheKeyFile, "utf-8")) === cacheKey) return output;
+  } catch {}
+
+  {
+    const buildScriptPath = join(dir, "build");
+    await writeFile(buildScriptPath, buildScript);
+    await chmod(buildScriptPath, 0o700);
+  }
+  await run(dir);
+  await writeFile(cacheKeyFile, cacheKey);
+
+  return output;
+}
diff --git a/services/forgejo/build.ts b/services/forgejo/build.ts
index 7857a44..d8a1644 100644
--- a/services/forgejo/build.ts
+++ b/services/forgejo/build.ts
@@ -1,25 +1,15 @@
 import { chmod, mkdir, readFile, writeFile } from "node:fs/promises";
 import { join } from "node:path";
-import { reproRun } from "../../helpers/repro-run.js";
+import { buildRepro, reproRun } from "../../helpers/repro-run.js";
 
 const FORGEJO_VERSION = "v1.18.3-0";
 
 // returns path to statically compiled binary
 export async function buildForgejo(): Promise<string> {
-  const dir = "cache/forgejo";
-  await mkdir(dir, { recursive: true });
-  const versionFile = join(dir, "version");
-  const output = join(dir, "rootfs/forgejo");
-  try {
-    if ((await readFile(versionFile, "utf-8")) === FORGEJO_VERSION)
-      return output;
-  } catch {}
-
-  {
-    const buildScript = join(dir, "build");
-    await writeFile(
-      buildScript,
-      `#!/bin/sh -e
+  return await buildRepro(
+    "forgejo",
+    FORGEJO_VERSION,
+    `#!/bin/sh -e
 runprint() {
   echo "==> $@"
   "$@"
@@ -33,20 +23,17 @@ cd forgejo
 
 runprint env GOOS=linux GOARCH=amd64 LDFLAGS="-linkmode external -extldflags '-static' $LDFLAGS" TAGS="bindata sqlite sqlite_unlock_notify" make build
 mv gitea /forgejo
-`
-    );
-    await chmod(buildScript, 0o700);
-  }
-  await reproRun({
-    cwd: dir,
-    command: "/src/build",
-    cache: [
-      "/home/repro/.cache/go-build",
-      "/home/repro/go",
-      "/home/repro/.npm",
-    ],
-  });
-  await writeFile(versionFile, FORGEJO_VERSION);
-
-  return output;
+`,
+    (dir) =>
+      reproRun({
+        cwd: dir,
+        command: "/src/build",
+        cache: [
+          "/home/repro/.cache/go-build",
+          "/home/repro/go",
+          "/home/repro/.npm",
+        ],
+      }),
+    (dir) => join(dir, "rootfs/forgejo")
+  );
 }
diff --git a/services/loki/build.ts b/services/loki/build.ts
index 17a3f2b..0e12925 100644
--- a/services/loki/build.ts
+++ b/services/loki/build.ts
@@ -1,24 +1,14 @@
-import { chmod, mkdir, readFile, writeFile } from "node:fs/promises";
 import { join } from "node:path";
-import { reproRun } from "../../helpers/repro-run.js";
+import { buildRepro, reproRun } from "../../helpers/repro-run.js";
 
 const LOKI_VERSION = "v2.7.3";
 
 // returns path to statically compiled binary
-export async function buildLoki(): Promise<string> {
-  const dir = "cache/loki";
-  await mkdir(dir, { recursive: true });
-  const versionFile = join(dir, "version");
-  const output = join(dir, "rootfs/loki");
-  try {
-    if ((await readFile(versionFile, "utf-8")) === LOKI_VERSION) return output;
-  } catch {}
-
-  {
-    const buildScript = join(dir, "build");
-    await writeFile(
-      buildScript,
-      `#!/bin/sh -e
+export function buildLoki(): Promise<string> {
+  return buildRepro(
+    "loki",
+    LOKI_VERSION,
+    `#!/bin/sh -e
 runprint() {
   echo "==> $@"
   "$@"
@@ -33,20 +23,17 @@ cd loki
 
 runprint make -j1 GOMOD=readonly logcli loki
 mv cmd/loki/loki /loki
-`
-    );
-    await chmod(buildScript, 0o700);
-  }
-  await reproRun({
-    cwd: dir,
-    command: "/src/build",
-    cache: [
-      "/home/repro/.cache/go-build",
-      "/home/repro/go",
-      "/home/repro/.npm",
-    ],
-  });
-  await writeFile(versionFile, LOKI_VERSION);
-
-  return output;
+`,
+    (dir) =>
+      reproRun({
+        cwd: dir,
+        command: "/src/build",
+        cache: [
+          "/home/repro/.cache/go-build",
+          "/home/repro/go",
+          "/home/repro/.npm",
+        ],
+      }),
+    (dir) => join(dir, "rootfs/loki")
+  );
 }