Left panel: interstellar flux (multiplied by E²) of primary positrons computed with all propagation effects (Φ^DM, solid lines) and with the high-energy approximation (, dotted lines) for a 10 TeV WIMP annihilating into pairs with ⟨ σv ⟩ =3 × 10^-26 cm³ s^-1, for the Min (blue), Med (red), and Max (green) models. Right panel: relative error above 10 GeV of the high-energy approximation for primary positrons compared to the exact result.