StructInitializer in Mux expressions

[fruffy]

I have a question about StructInitializers in Mux expressions:

control ingress(inout Headers h) {
    apply {
        h.eth_hdr = h.eth_hdr.eth_type == 1 ? {48w1, 48w1, 16w1} : {48w2, 48w2, 16w2};
    }
}

Is this legal? Currently, I get the error:

mux_validity.p4(29): [--Werror=type-error] error: AssignmentStatement: Cannot unify tuple_0 wi
th ethernet_t                                                                                                 
        h.eth_hdr = h.eth_hdr.eth_type == 1 ? {48w1, 48w1, 16w1} : {48w2, 48w2, 16w2};     

mux_initializer.p4.txt