diff --git a/chrome/content/zotero/xpcom/search.js b/chrome/content/zotero/xpcom/search.js
index a91da7ef1..02bffc7d5 100644
--- a/chrome/content/zotero/xpcom/search.js
+++ b/chrome/content/zotero/xpcom/search.js
@@ -440,7 +440,7 @@ Zotero.Search.prototype.removeCondition = function (searchConditionID) {
 	this._requireData('conditions');
 	
 	if (typeof this._conditions[searchConditionID] == 'undefined'){
-		throw ('Invalid searchConditionID ' + searchConditionID + ' in removeCondition()');
+		throw new Error('Invalid searchConditionID ' + searchConditionID + ' in removeCondition()');
 	}
 	
 	delete this._conditions[searchConditionID];
@@ -825,7 +825,7 @@ Zotero.Search.prototype.fromJSON = function (json) {
 	}
 	this.name = json.name;
 	
-	Object.keys(this.getConditions()).forEach(id => this.removeCondition(0));
+	Object.keys(this.getConditions()).forEach(id => this.removeCondition(id));
 	for (let i = 0; i < json.conditions.length; i++) {
 		let condition = json.conditions[i];
 		this.addCondition(
diff --git a/test/content/support.js b/test/content/support.js
index 8c5636cef..6b660f499 100644
--- a/test/content/support.js
+++ b/test/content/support.js
@@ -386,6 +386,7 @@ function createUnsavedDataObject(objectType, params = {}) {
 	
 	if (objectType == 'search') {
 		obj.addCondition('title', 'contains', Zotero.Utilities.randomString());
+		obj.addCondition('title', 'isNot', Zotero.Utilities.randomString());
 	}
 	
 	Zotero.Utilities.assignProps(obj, params, allowedParams);
diff --git a/test/tests/searchTest.js b/test/tests/searchTest.js
index 2d20f2b93..c62f31084 100644
--- a/test/tests/searchTest.js
+++ b/test/tests/searchTest.js
@@ -221,6 +221,7 @@ describe("Zotero.Search", function() {
 			let s = new Zotero.Search();
 			s.name = "Test";
 			s.addCondition('joinMode', 'any');
+			s.addCondition('title', 'isNot', 'foo');
 			let json = s.toJSON();
 			json.name = "Test 2";
 			json.conditions = [