The decay η′_c → η_cππ

It is pointed out that the decay of the recently observed charmonium η′_c resonance, η′_c → η_cππ is simply related to the well-studied decay ψ′ → J/ψππ and can thus be used for absolute normalization of other decay modes of the η′_c. The total rate of the discussed decay should be approximately three to four times the corresponding rate for the ψ′ resonance making the channel with charged pions the most probable exclusive decay mode of the η′_c with the branching ratio in the range 5-10%.