diff --git a/spec/integ/sliding-sync.spec.ts b/spec/integ/sliding-sync.spec.ts
index cc7a1d0dd..8c4a7ad12 100644
--- a/spec/integ/sliding-sync.spec.ts
+++ b/spec/integ/sliding-sync.spec.ts
@@ -584,7 +584,7 @@ describe("SlidingSync", () => {
             let txnId;
             httpBackend.when("POST", syncUrl).check(function(req) {
                 const body = req.data;
-                logger.log("txn got ", body);
+                logger.debug("got ", body);
                 expect(body.room_subscriptions).toBeTruthy();
                 expect(body.room_subscriptions[roomId]).toEqual(roomSubInfo);
                 expect(body.txn_id).toBeTruthy();
@@ -616,7 +616,7 @@ describe("SlidingSync", () => {
             let txnId;
             httpBackend.when("POST", syncUrl).check(function(req) {
                 const body = req.data;
-                logger.log("txn got ", body);
+                logger.debug("got ", body);
                 expect(body.room_subscriptions).toBeFalsy();
                 expect(body.lists[0]).toEqual(newList);
                 expect(body.txn_id).toBeTruthy();
@@ -638,7 +638,7 @@ describe("SlidingSync", () => {
             let txnId;
             httpBackend.when("POST", syncUrl).check(function(req) {
                 const body = req.data;
-                logger.log("txn got ", body);
+                logger.debug("got ", body);
                 expect(body.room_subscriptions).toBeFalsy();
                 expect(body.lists[0]).toEqual({
                     ranges: [[20, 40]],
@@ -664,7 +664,7 @@ describe("SlidingSync", () => {
             let txnId;
             httpBackend.when("POST", syncUrl).check(function(req) {
                 const body = req.data;
-                logger.log("txn got ", body);
+                logger.debug("got ", body);
                 expect(body.room_subscriptions).toBeTruthy();
                 expect(body.room_subscriptions[roomId]).toEqual({
                     timeline_limit: 99,
@@ -759,7 +759,7 @@ describe("SlidingSync", () => {
             let txnId;
             httpBackend.when("POST", syncUrl).check(function(req) {
                 const body = req.data;
-                logger.log("txn got ", body);
+                logger.debug("got ", body);
                 expect(body.room_subscriptions).toBeFalsy();
                 expect(body.lists[0]).toEqual({
                     ranges: [[20, 40]],
diff --git a/src/sliding-sync.ts b/src/sliding-sync.ts
index 9d5cefe02..28026b3a9 100644
--- a/src/sliding-sync.ts
+++ b/src/sliding-sync.ts
@@ -639,6 +639,10 @@ export class SlidingSync extends TypedEventEmitter<SlidingSyncEvent, SlidingSync
      * on failure.
      */
     public resend(): Promise<string> {
+        if (this.needsResend && this.txnIdDefers.length > 0) {
+            // we already have a resend queued, so just return the same promise
+            return this.txnIdDefers[this.txnIdDefers.length-1].promise;
+        }
         this.needsResend = true;
         this.txnId = this.client.makeTxnId();
         const d = defer<string>();
@@ -671,9 +675,7 @@ export class SlidingSync extends TypedEventEmitter<SlidingSyncEvent, SlidingSync
         // This list is sorted in time, so if the input txnId ACKs in the middle of this array,
         // then everything before it that hasn't been ACKed yet never will and we should reject them.
         for (let i = 0; i < txnIndex; i++) {
-            if (i < txnIndex) {
-                this.txnIdDefers[i].reject(this.txnIdDefers[i].txnId);
-            }
+            this.txnIdDefers[i].reject(this.txnIdDefers[i].txnId);
         }
         this.txnIdDefers[txnIndex].resolve(txnId);
         // clear out settled promises, incuding the one we resolved.