A clamp includes a base section, from which a pair of sidewalls and prongs extend, where the prongs are designed to grip gussets within the curb inlet and maintain proper alignment with designated portions of the restrictor plate despite manufacturing variations in gussets positioning within the curb inlet. The clamp is capable of securely positioning a floatable restrictor plate within or flush with an opening of the curb inlet so as to prevent floatables from entering storm sewer systems through the curb inlet.