Abstract: A miniature thermostatic switch of the type that can be inserted into the windings of electrical devices in order to sense the temperature of the windings is disclosed having an improved liquid tight seal to prevent seepage into the switch of varnish or other liquids to which the windings are subjected during assembly. The switch has a two part metallic housing with lips of one part clamped to the other part with an electrically insulating gasket interposed between the two parts. After assembly of the switch the gasket material is softened and the lip is subjected to a force to deform the gasket material, wetting the housing contiguous to the gasket and forming fillets therebetween to completely fill in any voids between the gasket and the contiguous housing.