diff --git a/src/module.ts b/src/module.ts
index af6e099..48ce5c9 100644
--- a/src/module.ts
+++ b/src/module.ts
@@ -70,13 +70,21 @@ export default defineNuxtModule<ModuleOptions>({
   },
   setup(options, nuxt) {
     const { resolve } = createResolver(import.meta.url);
+    
+    nuxt.options.runtimeConfig.posthog = defu(
+      nuxt.options.runtimeConfig.posthog,
+      {
+        publicKey: '',
+        host: '',
+      }
+    );
 
     // Public runtimeConfig
     nuxt.options.runtimeConfig.public.posthog = defu<ModuleOptions, ModuleOptions[]>(
       nuxt.options.runtimeConfig.public.posthog,
       {
-        publicKey: options.publicKey,
-        host: options.host,
+        publicKey: options.publicKey || nuxt.options.runtimeConfig.posthog.publicKey,
+        host: options.host || nuxt.options.runtimeConfig.posthog.host,
         capturePageViews: options.capturePageViews,
         capturePageLeaves: options.capturePageLeaves,
         clientOptions: options.clientOptions,