diff --git a/src/interpolation_methods.jl b/src/interpolation_methods.jl
index a92fcaa7..b729ad52 100644
--- a/src/interpolation_methods.jl
+++ b/src/interpolation_methods.jl
@@ -140,7 +140,7 @@ end
 # BSpline Curve Interpolation
 function (A::BSplineInterpolation{<:AbstractVector{<:Number}})(t::Number)
   # change t into param [0 1]
-  idx = findfirst(x->x>=t,A.t) - 1
+  idx = searchsortedlast(A.t,t)
   idx == 0 ? idx += 1 : nothing
   t = A.p[idx] + (t - A.t[idx])/(A.t[idx+1] - A.t[idx]) * (A.p[idx+1] - A.p[idx])
   n = length(A.t)
@@ -155,7 +155,7 @@ end
 # BSpline Curve Approx
 function (A::BSplineApprox{<:AbstractVector{<:Number}})(t::Number)
   # change t into param [0 1]
-  idx = findfirst(x->x>=t,A.t) - 1
+  idx = searchsortedlast(A.t,t)
   idx == 0 ? idx += 1 : nothing
   t = A.p[idx] + (t - A.t[idx])/(A.t[idx+1] - A.t[idx]) * (A.p[idx+1] - A.p[idx])
   n = length(A.t)