The equiatomic high-entropy alloy Cr₂₀Mn₂₀Fe₂₀Co₂₀Ni₂₀ high-entropy alloy has a valence-electron-concentration of 8 electrons/atom which is equivalent to that of Fe. The alloy being FCC is therefore electronically equivalent to FCC-Fe. We show through the thermal expansion properties that the alloy carries similar anti-Invar properties as FCC-Fe, but unlike FCC-Fe it is stable throughout its solid-state temperaturerange. Therefore, by exploiting the anti-Invar property and expanding the lattice of the alloy by introducing interstitial carbon, we make Cr₂₀Mn₂₀Fe₂₀Co₂₀Ni₂₀ ferromagnetic with a Curie temperature lying above room temperature.