diff --git a/.lycheeignore b/.lycheeignore
index d04e68074..4c781f6a0 100644
--- a/.lycheeignore
+++ b/.lycheeignore
@@ -9,7 +9,7 @@ https://mkdocs.org/
 https://osawards.com/javascript/#nominees
 https://osawards.com/javascript/2019
 
-# Timeout error, maybe Twitter has anti-bot defences against GitHub's CI servers?
+# Timeout error, maybe Twitter has anti-bot defenses against GitHub's CI servers?
 https://twitter.com/mermaidjs_
 
 # Don't check files that are generated during the build via `pnpm docs:code`
diff --git a/docs/config/setup/modules/mermaidAPI.md b/docs/config/setup/modules/mermaidAPI.md
index 8b24a8917..5bedb8954 100644
--- a/docs/config/setup/modules/mermaidAPI.md
+++ b/docs/config/setup/modules/mermaidAPI.md
@@ -95,7 +95,7 @@ mermaid.initialize(config);
 
 #### Defined in
 
-[mermaidAPI.ts:659](https://github.com/mermaid-js/mermaid/blob/master/packages/mermaid/src/mermaidAPI.ts#L659)
+[mermaidAPI.ts:662](https://github.com/mermaid-js/mermaid/blob/master/packages/mermaid/src/mermaidAPI.ts#L662)
 
 ## Functions
 
diff --git a/packages/mermaid/src/mermaidAPI.ts b/packages/mermaid/src/mermaidAPI.ts
index 66bc99e5e..191fc672b 100644
--- a/packages/mermaid/src/mermaidAPI.ts
+++ b/packages/mermaid/src/mermaidAPI.ts
@@ -558,7 +558,10 @@ const render = async function (
 function initialize(options: MermaidConfig = {}) {
   // Handle legacy location of font-family configuration
   if (options?.fontFamily && !options.themeVariables?.fontFamily) {
-    options.themeVariables = { fontFamily: options.fontFamily };
+    if (!options.themeVariables) {
+      options.themeVariables = {};
+    }
+    options.themeVariables.fontFamily = options.fontFamily;
   }
 
   // Set default options