diff --git a/index.d.ts b/index.d.ts
index 6615b02..3802c46 100644
--- a/index.d.ts
+++ b/index.d.ts
@@ -1415,6 +1415,8 @@ declare class SQLite3Error extends Error {
 /** A pointer to a location in WASM heap memory. */
 declare type WasmPointer = number;
 
+declare type NullPointer = 0 | null | undefined;
+
 declare type StructPtrMapper<T> = {
   StructType: T;
   /**
@@ -6548,7 +6550,7 @@ declare type CAPI = {
    *
    * See https://www.sqlite.org/session/sqlite3session_attach.html
    */
-  sqlite3session_attach: (pSession: WasmPointer, tableName: string) => number;
+  sqlite3session_attach: (pSession: WasmPointer, tableName: string | NullPointer) => number;
 
   /**
    * Set a table filter on a Session Object.