diff --git a/packages/taler-integrationtests/src/harness.ts b/packages/taler-integrationtests/src/harness.ts
index 753e10e7e..df2d9f2e7 100644
--- a/packages/taler-integrationtests/src/harness.ts
+++ b/packages/taler-integrationtests/src/harness.ts
@@ -885,7 +885,7 @@ export class ExchangeService implements ExchangeServiceInterface {
 
     this.exchangeHttpProc = this.globalState.spawnService(
       "taler-exchange-httpd",
-      ["-c", this.configFilename],
+      ["-c", this.configFilename, "--num-threads", "1"],
       `exchange-httpd-${this.name}`,
     );
   }