diff --git a/sqlite3.go b/sqlite3.go
index 71a791f..cfbdae3 100644
--- a/sqlite3.go
+++ b/sqlite3.go
@@ -383,7 +383,7 @@ func (c *SQLiteConn) RegisterFunc(name string, impl interface{}, pure bool) erro
 	if pure {
 		opts |= C.SQLITE_DETERMINISTIC
 	}
-	rv := sqlite3_create_function(c.db, cname, numArgs, opts, newHandle(c, &fi), C.callbackTrampoline, nil, nil)
+	rv := sqlite3_create_function(c.db, cname, C.int(numArgs), C.int(opts), C.uintptr_t(newHandle(c, &fi)), C.callbackTrampoline, nil, nil)
 	if rv != C.SQLITE_OK {
 		return c.lastError()
 	}