diff --git a/abstract-relay.ts b/abstract-relay.ts
index 1f26c42..0baf0d0 100644
--- a/abstract-relay.ts
+++ b/abstract-relay.ts
@@ -342,10 +342,7 @@ export class AbstractRelay {
       this.ongoingOperations++
     }
 
-    this.serial++
-    const id = params.id || (params.label ? params.label + ':' : 'sub:') + this.serial
-    const sub = new Subscription(this, id, filters, params)
-    this.openSubs.set(id, sub)
+    const sub = this.prepareSubscription(filters, params)
     sub.fire()
 
     if (params.abort) {
@@ -355,6 +352,17 @@ export class AbstractRelay {
     return sub
   }
 
+  public prepareSubscription(
+    filters: Filter[],
+    params: Partial<SubscriptionParams> & { label?: string; id?: string },
+  ): Subscription {
+    this.serial++
+    const id = params.id || (params.label ? params.label + ':' : 'sub:') + this.serial
+    const sub = new Subscription(this, id, filters, params)
+    this.openSubs.set(id, sub)
+    return sub
+  }
+
   public close() {
     this.skipReconnection = true
     if (this.reconnectTimeoutHandle) {