diff --git a/src/imessage/client.test.ts b/src/imessage/client.test.ts
new file mode 100644
index 00000000000..b755b060e37
--- /dev/null
+++ b/src/imessage/client.test.ts
@@ -0,0 +1,22 @@
+import { beforeEach, describe, expect, it, vi } from "vitest";
+
+const spawnMock = vi.hoisted(() => vi.fn());
+
+vi.mock("node:child_process", () => ({
+  spawn: (...args: unknown[]) => spawnMock(...args),
+}));
+
+describe("createIMessageRpcClient", () => {
+  beforeEach(() => {
+    spawnMock.mockReset();
+    vi.stubEnv("VITEST", "true");
+  });
+
+  it("refuses to spawn imsg rpc in test environments", async () => {
+    const { createIMessageRpcClient } = await import("./client.js");
+    await expect(createIMessageRpcClient()).rejects.toThrow(
+      /Refusing to start imsg rpc in test environment/i,
+    );
+    expect(spawnMock).not.toHaveBeenCalled();
+  });
+});
diff --git a/src/imessage/client.ts b/src/imessage/client.ts
index 1a47f172604..d4ec458a7e9 100644
--- a/src/imessage/client.ts
+++ b/src/imessage/client.ts
@@ -37,6 +37,14 @@ type PendingRequest = {
   timer?: NodeJS.Timeout;
 };
 
+function isTestEnv(): boolean {
+  if (process.env.NODE_ENV === "test") {
+    return true;
+  }
+  const vitest = process.env.VITEST?.trim().toLowerCase();
+  return Boolean(vitest);
+}
+
 export class IMessageRpcClient {
   private readonly cliPath: string;
   private readonly dbPath?: string;
@@ -63,6 +71,9 @@ export class IMessageRpcClient {
     if (this.child) {
       return;
     }
+    if (isTestEnv()) {
+      throw new Error("Refusing to start imsg rpc in test environment; mock iMessage RPC client");
+    }
     const args = ["rpc"];
     if (this.dbPath) {
       args.push("--db", this.dbPath);