diff --git a/index.d.ts b/index.d.ts
index 55637511..1d2f1606 100644
--- a/index.d.ts
+++ b/index.d.ts
@@ -2,13 +2,13 @@ export function parse(connectionString: string): ConnectionOptions;
 
 export interface ConnectionOptions {
   host: string | null;
-  password: string | null;
-  user: string | null;
-  port: number | null;
-  database: string | null;
-  client_encoding: string | null;
-  ssl: boolean | null;
+  password?: string;
+  user?: string;
+  port?: string | null;
+  database: string | null | undefined;
+  client_encoding?: string;
+  ssl?: boolean | string;
 
-  application_name: string | null;
-  fallback_application_name: string | null;
+  application_name?: string;
+  fallback_application_name?: string;
 }