diff --git a/src/cache/core/types/Cache.ts b/src/cache/core/types/Cache.ts
index 281e0a1599a..6389d121bd5 100644
--- a/src/cache/core/types/Cache.ts
+++ b/src/cache/core/types/Cache.ts
@@ -28,6 +28,7 @@ export namespace Cache {
   export interface WatchOptions extends ReadOptions {
     immediate?: boolean;
     callback: WatchCallback;
+    lastDiff?: DiffResult<any>;
   }
 
   export interface EvictOptions {
diff --git a/src/cache/inmemory/__tests__/cache.ts b/src/cache/inmemory/__tests__/cache.ts
index 5206b2ff00c..6545a68dba1 100644
--- a/src/cache/inmemory/__tests__/cache.ts
+++ b/src/cache/inmemory/__tests__/cache.ts
@@ -1492,22 +1492,11 @@ describe('Cache', () => {
       expect(dirtied.has(abInfo.watch)).toBe(true);
       expect(dirtied.has(bInfo.watch)).toBe(false);
 
-      expect(last(aInfo.diffs)).toEqual({
-        complete: true,
-        result: {
-          a: "ay",
-        },
-      });
-
-      expect(last(abInfo.diffs)).toEqual({
-        complete: true,
-        result: {
-          a: "ay",
-          b: "bee",
-        },
-      });
-
-      expect(bInfo.diffs.length).toBe(0);
+      // No new diffs should have been generated, since we only invalidated
+      // fields using cache.modify, and did not change any field values.
+      expect(aInfo.diffs).toEqual([]);
+      expect(abInfo.diffs).toEqual([]);
+      expect(bInfo.diffs).toEqual([]);
 
       aInfo.cancel();
       abInfo.cancel();
@@ -1686,7 +1675,6 @@ describe("InMemoryCache#broadcastWatches", function () {
     expect(receivedCallbackResults).toEqual([
       received1,
       // New results:
-      received1,
       received2,
     ]);
 
@@ -1714,7 +1702,6 @@ describe("InMemoryCache#broadcastWatches", function () {
     }];
 
     expect(receivedCallbackResults).toEqual([
-      received1,
       received1,
       received2,
       // New results:
@@ -1734,16 +1721,12 @@ describe("InMemoryCache#broadcastWatches", function () {
     }];
 
     expect(receivedCallbackResults).toEqual([
-      received1,
       received1,
       received2,
       received3,
       received4,
       // New results:
-      received1,
       received2AllCaps,
-      received3,
-      received4,
     ]);
   });
 });
diff --git a/src/cache/inmemory/__tests__/readFromStore.ts b/src/cache/inmemory/__tests__/readFromStore.ts
index b546b4d1f5a..2a25c064df9 100644
--- a/src/cache/inmemory/__tests__/readFromStore.ts
+++ b/src/cache/inmemory/__tests__/readFromStore.ts
@@ -1419,10 +1419,10 @@ describe('reading from the store', () => {
 
     const diffs: Cache.DiffResult<any>[] = [];
 
-    function watch() {
+    function watch(immediate = true) {
       return cache.watch({
         query: rulerQuery,
-        immediate: true,
+        immediate,
         optimistic: true,
         callback(diff) {
           diffs.push(diff);
@@ -1764,14 +1764,10 @@ describe('reading from the store', () => {
       diffWithZeusAsRuler,
     ]);
 
-    // Rewatch the rulerQuery, which will populate the same diffs array
-    // that we were using before.
-    const cancel2 = watch();
-
-    const diffWithApolloAsRuler = {
-      complete: true,
-      result: apolloRulerResult,
-    };
+    // Rewatch the rulerQuery, but avoid delivering an immediate initial
+    // result (by passing false), so that we can use cache.modify to
+    // trigger the delivery of diffWithApolloAsRuler below.
+    const cancel2 = watch(false);
 
     expect(diffs).toEqual([
       initialDiff,
@@ -1779,7 +1775,6 @@ describe('reading from the store', () => {
       diffWithoutDevouredSons,
       diffWithChildrenOfZeus,
       diffWithZeusAsRuler,
-      diffWithApolloAsRuler,
     ]);
 
     cache.modify({
@@ -1797,6 +1792,11 @@ describe('reading from the store', () => {
 
     cancel2();
 
+    const diffWithApolloAsRuler = {
+      complete: true,
+      result: apolloRulerResult,
+    };
+
     // The cache.modify call should have triggered another diff, since we
     // overwrote the ROOT_QUERY.ruler field with a valid Reference to the
     // Apollo entity object.
@@ -1807,7 +1807,6 @@ describe('reading from the store', () => {
       diffWithChildrenOfZeus,
       diffWithZeusAsRuler,
       diffWithApolloAsRuler,
-      diffWithApolloAsRuler,
     ]);
 
     expect(
diff --git a/src/cache/inmemory/inMemoryCache.ts b/src/cache/inmemory/inMemoryCache.ts
index dc62df90e1e..99b0107880b 100644
--- a/src/cache/inmemory/inMemoryCache.ts
+++ b/src/cache/inmemory/inMemoryCache.ts
@@ -446,6 +446,8 @@ export class InMemoryCache extends ApolloCache<NormalizedCacheObject> {
       }
     }
 
-    c.callback(diff);
+    if (!c.lastDiff || c.lastDiff.result !== diff.result) {
+      c.callback(c.lastDiff = diff);
+    }
   }
 }