diff --git a/chrome/content/zotero/xpcom/sync/syncEngine.js b/chrome/content/zotero/xpcom/sync/syncEngine.js
index 620d5b32ea..0f3ebebe1f 100644
--- a/chrome/content/zotero/xpcom/sync/syncEngine.js
+++ b/chrome/content/zotero/xpcom/sync/syncEngine.js
@@ -1240,6 +1240,7 @@ Zotero.Sync.Data.Engine.prototype._uploadObjects = Zotero.Promise.coroutine(func
 						}
 					}
 					
+					// Successful
 					if (state == 'successful') {
 						// Update local object with saved data if necessary, as long as it hasn't
 						// changed locally since the upload
@@ -1253,14 +1254,24 @@ Zotero.Sync.Data.Engine.prototype._uploadObjects = Zotero.Promise.coroutine(func
 						}
 						toCache.push(current);
 					}
+					// Unchanged
 					else {
-						// This won't necessarily reflect the actual version of the object on the server,
-						// since objects are uploaded in batches and we only get the final version, but it
-						// will guarantee that the item won't be redownloaded unnecessarily in the case of
-						// a full sync, because the version will be higher than whatever version is on the
-						// server.
-						jsonBatch[index].version = libraryVersion;
-						toCache.push(jsonBatch[index]);
+						// If a cache object exists, there shouldn't be any need to update it, since
+						// nothing was changed on the server, including the version.
+						//
+						// If there's no cache object, we can save the uploaded object, which we know
+						// matches what's on the server. The version number won't necessarily reflect
+						// the actual version of the object on the server, since objects are uploaded
+						// in batches and we only get the final version, but it will guarantee that
+						// the object won't be redownloaded unnecessarily in the case of a full sync,
+						// because the version will be higher than whatever version is on the server.
+						let hasCacheObject = !!Zotero.Sync.Data.Local.getCacheObject(
+							objectType, obj.libraryID, obj.key, obj.version
+						);
+						if (!hasCacheObject) {
+							jsonBatch[index].version = libraryVersion;
+							toCache.push(jsonBatch[index]);
+						}
 					}
 					
 					numSuccessful++;
diff --git a/test/tests/syncEngineTest.js b/test/tests/syncEngineTest.js
index 9d5fe4841a..f202546f32 100644
--- a/test/tests/syncEngineTest.js
+++ b/test/tests/syncEngineTest.js
@@ -801,6 +801,56 @@ describe("Zotero.Sync.Data.Engine", function () {
 		});
 		
 		
+		it("shouldn't update existing cache object after upload on 'unchanged' response", async function () {
+			({ engine, client, caller } = await setup());
+			
+			var library = Zotero.Libraries.userLibrary;
+			var lastLibraryVersion = 5;
+			library.libraryVersion = lastLibraryVersion;
+			await library.saveTx();
+			
+			var item = await createDataObject('item', { version: 1, title: "A" });
+			var json = item.toJSON();
+			// Save current version to cache so the patch object is empty, as if the item had been
+			// added to a collection and removed from it (such that even dateModified didn't change)
+			await Zotero.Sync.Data.Local.saveCacheObjects('item', library.id, [json]);
+			
+			server.respond(function (req) {
+				if (req.method == "POST" && req.url == baseURL + "users/1/items") {
+					let json = JSON.parse(req.requestBody);
+					req.respond(
+						200,
+						{
+							"Content-Type": "application/json",
+							"Last-Modified-Version": ++lastLibraryVersion
+						},
+						JSON.stringify({
+							successful: {},
+							unchanged: {
+								"0": item.key
+							},
+							failed: {}
+						})
+					);
+					return;
+				}
+			});
+			
+			await engine.start();
+			
+			// Check data in cache
+			var version = await Zotero.Sync.Data.Local.getLatestCacheObjectVersion(
+				'item', library.id, item.key
+			);
+			assert.equal(version, 1);
+			json = await Zotero.Sync.Data.Local.getCacheObject(
+				'item', library.id, item.key, 1
+			);
+			assert.propertyVal(json.data, 'itemType', 'book');
+			assert.propertyVal(json.data, 'title', 'A');
+		});
+		
+		
 		it("should upload child collection after parent collection", function* () {
 			({ engine, client, caller } = yield setup());