A generally rectangular shingle tab cover panel is provided for securement over each shingle tab to be covered and each cover panel includes a lower edge, an upper edge and side margins extending between the upper and lower edges. One of the side margins includes a downturned flange and the other side margin includes a downwardly depressed channel spaced slightly inward from the free marginal edge thereof. Each cover panel is applied over a corresponding shingle tab with the depending side marginal flange closely outward of the corresponding side edge of the associated shingle tab and the downwardly depressed channel received in the spacing between the other side edge of the corresponding shingle tab and the opposing side edge of the next adjacent shingle tab. The upper edge of the cover panel is inserted beneath the lower edges of the adjacent shingle tabs in the next upper course of shingle tabs and roofing nails are driven downward through the adjacent lower corner portions of the aforementioned adjacent next upper shingle tabs and also downwardly through longitudinally spaced central upper marginal portions of the cover panel.