diff --git a/src/DataInterpolations.jl b/src/DataInterpolations.jl
index 16b003f7..fa82c622 100644
--- a/src/DataInterpolations.jl
+++ b/src/DataInterpolations.jl
@@ -22,7 +22,7 @@ include("show.jl")
 (interp::AbstractInterpolation)(t::Number) = _interpolate(interp, t)
 (interp::AbstractInterpolation)(t::Number, i::Integer) = _interpolate(interp, t, i)
 function (interp::AbstractInterpolation)(t::AbstractVector)
-    interp(similar(t, promote_type(eltype(interp), eltype(t))), t)
+    interp(similar(t, promote_type(eltype(interp.u), eltype(t))), t)
 end
 function (interp::AbstractInterpolation)(u::AbstractVector, t::AbstractVector)
     iguess = firstindex(interp.t)