diff --git a/ts/output/chtml.ts b/ts/output/chtml.ts
index 9f41a5d15..92d63d859 100644
--- a/ts/output/chtml.ts
+++ b/ts/output/chtml.ts
@@ -155,7 +155,7 @@ CommonOutputJax<
    * @override
    * @constructor
    */
-  constructor(options: OptionList = null) {
+  constructor(options: OptionList = {}) {
     super(options, ChtmlWrapperFactory as any, DefaultFont);
     this.font.adaptiveCSS(this.options.adaptiveCSS);
     this.wrapperUsage = new Usage<string>();
diff --git a/ts/output/common.ts b/ts/output/common.ts
index 290f4f008..d0f9a0f53 100644
--- a/ts/output/common.ts
+++ b/ts/output/common.ts
@@ -233,7 +233,7 @@ export abstract class CommonOutputJax<
    * @param {FC} defaultFont                       The default FontData constructor
    * @constructor
    */
-  constructor(options: OptionList = null,
+  constructor(options: OptionList = {},
               defaultFactory: typeof CommonWrapperFactory = null,
               defaultFont: FC = null) {
     const [fontClass, font] = (options.fontData instanceof FontData ?
diff --git a/ts/output/svg.ts b/ts/output/svg.ts
index fdd58ff54..b32a49348 100644
--- a/ts/output/svg.ts
+++ b/ts/output/svg.ts
@@ -140,7 +140,7 @@ CommonOutputJax<
    * @override
    * @constructor
    */
-  constructor(options: OptionList = null) {
+  constructor(options: OptionList = {}) {
     super(options, SvgWrapperFactory as any, DefaultFont);
     this.fontCache = new FontCache(this);
   }