diff --git a/dist/tab.js b/dist/tab.js
index 9fe1d1b6fe8b0172251ce7688f742bbb6c3b6da9..5dba20d6f551ec644eb168db95b45e48935879db 100644
--- a/dist/tab.js
+++ b/dist/tab.js
@@ -111,8 +111,8 @@ export class Tab extends EventTarget {
                     // leader when it died — we are the leader now, so dispatch them to
                     // ourselves (see the matching re-delivery for non-leader tabs in
                     // `_onLeader`; the same at-least-once caveat applies).
-                    this._callDeferreds.forEach(({ name, rest }, callNumber) => {
-                        if (queued.has(`${this._id}:${callNumber}`))
+                    this._callDeferreds.forEach(({ awaitingLeader, name, rest }, callNumber) => {
+                        if (awaitingLeader || queued.has(`${this._id}:${callNumber}`))
                             return;
                         this._clearSentCall(callNumber);
                         this._onCall(this._id, callNumber, name, ...rest);
@@ -141,8 +141,12 @@ export class Tab extends EventTarget {
                 this._clearSentCall(callNumber);
                 reject(new Error('Call timed out'));
             }, this._callTimeout);
-            this._callDeferreds.set(callNumber, { resolve, reject, timeout, name, rest });
+            this._callDeferreds.set(callNumber, { awaitingLeader: true, resolve, reject, timeout, name, rest });
             const hasLeader = await this.hasLeader();
+            const deferred = this._callDeferreds.get(callNumber);
+            if (!deferred)
+                return;
+            deferred.awaitingLeader = false;
             try {
                 if (this.isLeader && this._isLeaderReady) {
                     this._onCall(this._id, callNumber, name, ...rest);
@@ -294,8 +298,9 @@ export class Tab extends EventTarget {
         if (this._sentCalls.get(callNumber))
             this._callReceived(callNumber);
         const deferred = this._callDeferreds.get(callNumber);
+        // Delivery is at-least-once, so a duplicate or late return can arrive after the call has already settled.
         if (!deferred)
-            return console.error('No deferred found for call', callNumber);
+            return;
         clearTimeout(deferred.timeout);
         this._callDeferreds.delete(callNumber);
         if (error)
@@ -345,8 +350,8 @@ export class Tab extends EventTarget {
         // The same duplication happens inside a single election: a call queued while the leader was still initializing
         // is dispatched by that leader AND re-sent from here, because the leader's `onLeader` broadcast goes out
         // synchronously while the queued call's `onReturn` is still awaiting the handler.
-        this._callDeferreds.forEach(({ name, rest }, callNumber) => {
-            if (queued.has(`${this._id}:${callNumber}`) || this._sentCalls.has(callNumber))
+        this._callDeferreds.forEach(({ awaitingLeader, name, rest }, callNumber) => {
+            if (awaitingLeader || queued.has(`${this._id}:${callNumber}`) || this._sentCalls.has(callNumber))
                 return;
             try {
                 this._sendCall(callNumber, name, rest);
diff --git a/src/tab.ts b/src/tab.ts
index 3d42674d6276ff707b890d8009d0af22298f00c3..57d4fa50d46a7e2195ea9e51de4586c90a62de2e 100644
--- a/src/tab.ts
+++ b/src/tab.ts
@@ -7,4 +7,6 @@ interface Deferred {
 interface Deferred {
+  /** The original call is still waiting for `hasLeader()` to select its first delivery path. */
+  awaitingLeader: boolean;
   resolve: (value: any) => void;
   reject: (reason?: any) => void;
   timeout: number;
@@ -166,8 +168,8 @@ export class Tab<T = Record<string, any>> extends EventTarget implements Tab {
           // leader when it died — we are the leader now, so dispatch them to
           // ourselves (see the matching re-delivery for non-leader tabs in
           // `_onLeader`; the same at-least-once caveat applies).
-          this._callDeferreds.forEach(({ name, rest }, callNumber) => {
-            if (queued.has(`${this._id}:${callNumber}`)) return;
+          this._callDeferreds.forEach(({ awaitingLeader, name, rest }, callNumber) => {
+            if (awaitingLeader || queued.has(`${this._id}:${callNumber}`)) return;
             this._clearSentCall(callNumber);
             this._onCall(this._id, callNumber, name, ...rest);
           });
@@ -194,8 +196,11 @@ export class Tab<T = Record<string, any>> extends EventTarget implements Tab {
         this._clearSentCall(callNumber);
         reject(new Error('Call timed out'));
       }, this._callTimeout);
-      this._callDeferreds.set(callNumber, { resolve, reject, timeout, name, rest });
+      this._callDeferreds.set(callNumber, { awaitingLeader: true, resolve, reject, timeout, name, rest });
       const hasLeader = await this.hasLeader();
+      const deferred = this._callDeferreds.get(callNumber);
+      if (!deferred) return;
+      deferred.awaitingLeader = false;
       try {
         if (this.isLeader && this._isLeaderReady) {
           this._onCall(this._id, callNumber, name, ...rest);
@@ -337,7 +342,8 @@ export class Tab<T = Record<string, any>> extends EventTarget implements Tab {
   _onReturn(callNumber: number, error: any, results: any) {
     if (this._sentCalls.get(callNumber)) this._callReceived(callNumber);
     const deferred = this._callDeferreds.get(callNumber);
-    if (!deferred) return console.error('No deferred found for call', callNumber);
+    // Delivery is at-least-once, so a duplicate or late return can arrive after the call has already settled.
+    if (!deferred) return;
     clearTimeout(deferred.timeout);
     this._callDeferreds.delete(callNumber);
     if (error) deferred.reject(error);
@@ -386,8 +392,8 @@ export class Tab<T = Record<string, any>> extends EventTarget implements Tab {
     // The same duplication happens inside a single election: a call queued while the leader was still initializing
     // is dispatched by that leader AND re-sent from here, because the leader's `onLeader` broadcast goes out
     // synchronously while the queued call's `onReturn` is still awaiting the handler.
-    this._callDeferreds.forEach(({ name, rest }, callNumber) => {
-      if (queued.has(`${this._id}:${callNumber}`) || this._sentCalls.has(callNumber)) return;
+    this._callDeferreds.forEach(({ awaitingLeader, name, rest }, callNumber) => {
+      if (awaitingLeader || queued.has(`${this._id}:${callNumber}`) || this._sentCalls.has(callNumber)) return;
       try {
         this._sendCall(callNumber, name, rest);
       } catch (e) {