diff --git a/src/core.jl b/src/core.jl
index 2df0f60..3eae9ee 100755
--- a/src/core.jl
+++ b/src/core.jl
@@ -262,9 +262,9 @@ Cosmology(cpar::CosmoPar, settings::Settings; kwargs...) = begin
     # Distance to LSS
     chi_LSS = chis[end]
     # OPT: tolerances, interpolation method
-    chii = linear_interpolation(zs_chi, Vector(chis), extrapolation_bc=Line())
-    ti = linear_interpolation(zs_chi, Vector(ts), extrapolation_bc=Line())
-    zi = linear_interpolation(chis, Vector(zs_chi), extrapolation_bc=Line())
+    chii = cubic_spline_interpolation(zs, chis, extrapolation_bc=Line())
+    zi = linear_interpolation(chis, zs, extrapolation_bc=Line())
+    ti = linear_interpolation(zs_chi, ts, extrapolation_bc=Line())
     Dzs, Dzi, fs8zi = get_growth(cpar, settings; kwargs...)
 
     if settings.Pk_mode == :linear