diff --git a/dashboard/src/modules/config-store/store-github-builds.server.ts b/dashboard/src/modules/config-store/store-github-builds.server.ts
index 1b591304da..807fd1d41d 100644
--- a/dashboard/src/modules/config-store/store-github-builds.server.ts
+++ b/dashboard/src/modules/config-store/store-github-builds.server.ts
@@ -7,6 +7,7 @@ import type { StoreRefused } from "#/modules/config-store/store.contract";
 import { pinStoreSources } from "#/modules/config-store/store-deployment.server";
 import { organizationAccess } from "#/modules/github/github-access";
 import { cancelGithubRun, checkGithubBuildWorkflow, dispatchGithubBuildWorkflow, githubRunCompleted } from "#/modules/github/github-build.server";
+import { githubBuildId } from "#/modules/github/github-build-workflow";
 import { verifyGithubOidcToken } from "#/modules/github/github-oidc.server";
 import { installationRefusal } from "#/modules/github/github-token.server";
 import { sendInngestEvent } from "#/modules/inngest/client";
@@ -86,7 +87,7 @@ export const planStoreGithubBuilds = Effect.fn("StoreGithub.plan")(function* (da
     const walk = servers ? source.builders : source.builders.filter((builder) => builder !== "servers");
     if (walk[0] !== "github") return [];
     return [{
-      build: `${data.deploymentId}.${source.service}`,
+      build: githubBuildId(data.deploymentId, source.service),
       service: source.service,
       repository: source.repository,
       repositoryId: source.repository_id,
diff --git a/dashboard/src/modules/github/github-build-workflow.ts b/dashboard/src/modules/github/github-build-workflow.ts
index b9200308be..9294816edc 100644
--- a/dashboard/src/modules/github/github-build-workflow.ts
+++ b/dashboard/src/modules/github/github-build-workflow.ts
@@ -25,6 +25,10 @@ jobs:
           cloud: \${{ inputs.cloud }}
 `;
 
+export function githubBuildId(deploymentId: string, service: string) {
+  return `${deploymentId}.${service}`;
+}
+
 /**
  * Readiness of one repository for GitHub builds, as Cloud last checked it.
  * `waiting` (Add workflow opened, commit not seen yet) is only known to the browser that opened it.
diff --git a/dashboard/src/modules/github/github-build.test.ts b/dashboard/src/modules/github/github-build.test.ts
index a62232a425..1b685fabd5 100644
--- a/dashboard/src/modules/github/github-build.test.ts
+++ b/dashboard/src/modules/github/github-build.test.ts
@@ -2,7 +2,7 @@ import { Effect, Schema } from "effect";
 import { describe, expect, it } from "vitest";
 import { organizationAccess } from "./github-access";
 import { checkGithubBuildWorkflow } from "./github-build.server";
-import { GITHUB_BUILD_WORKFLOW, githubBuildWorkflowUrl } from "./github-build-workflow";
+import { GITHUB_BUILD_WORKFLOW, githubBuildId, githubBuildWorkflowUrl } from "./github-build-workflow";
 import { GithubApi, GithubObservationError, type GithubObservationErrorCode } from "./github-observation.api";
 
 describe("GitHub build workflow", () => {
@@ -13,6 +13,14 @@ describe("GitHub build workflow", () => {
     }
   });
 
+  it("dispatches build ids that getployz/build@v1 accepts", () => {
+    const accepted = /^[A-Za-z0-9_-][A-Za-z0-9._-]{0,127}$/;
+    const deployment = "36755d9a-dc30-4385-a9bd-86ae1a85e44b";
+    for (const service of ["a", "ployz-soak-node", "s".repeat(63)]) {
+      expect(githubBuildId(deployment, service)).toMatch(accepted);
+    }
+  });
+
   it("opens GitHub's new-file page on the default branch with the workflow filled in", () => {
     const url = new URL(githubBuildWorkflowUrl({ web: "http://127.0.0.1:4555", fullName: "acme/api", defaultBranch: "release/v2" }));
     expect(url.origin + url.pathname).toBe("http://127.0.0.1:4555/acme/api/new/release/v2");