diff --git a/smoke/run.test.ts b/smoke/run.test.ts
index d9b6c7274..7a46ec00e 100644
--- a/smoke/run.test.ts
+++ b/smoke/run.test.ts
@@ -128,12 +128,14 @@ let server: Server | null = null;
 let disconnect: (() => void) | null = null;
 let base = "";
 
-afterEach(() => {
+afterEach(async () => {
   // As switching projects does: run ids restart with each server.
   resetRuns();
   disconnect?.();
-  server?.close();
-  if (base) rmSync(base, { recursive: true, force: true, maxRetries: 5, retryDelay: 200 });
+  await server?.close();
+  // A language server's own process (jdtls's JVM) can outlive the server's for a moment:
+  // deleting its data directory has to wait for it.
+  if (base) rmSync(base, { recursive: true, force: true, maxRetries: 10, retryDelay: 1000 });
 });
 
 async function open(c: Case): Promise<string> {
diff --git a/smoke/server.ts b/smoke/server.ts
index 241e8130a..af387c384 100644
--- a/smoke/server.ts
+++ b/smoke/server.ts
@@ -78,9 +78,14 @@ export class Server {
     }
   }
 
-  close() {
-    this.child.stdin.end();
-    this.child.kill();
+  /** Kills the server; resolves once the process is gone (its children may still be exiting). */
+  async close(): Promise<void> {
+    if (this.child.exitCode === null && !this.child.killed) {
+      const exited = new Promise<void>((resolve) => this.child.once("exit", () => resolve()));
+      this.child.stdin.end();
+      this.child.kill();
+      await exited;
+    }
   }
 
   private request(method: string, params: unknown): Promise<unknown> {