diff --git a/src/integrals.jl b/src/integrals.jl
index 0e796d4d..e932bc5b 100644
--- a/src/integrals.jl
+++ b/src/integrals.jl
@@ -14,7 +14,7 @@ function integral(A::AbstractInterpolation, t1::Number, t2::Number)
     if A.t[idx2] == t2
         idx2 -= 1
     end
-    total = zero(eltype(A))
+    total = zero(eltype(A.u))
     for idx in idx1:idx2
         lt1 = idx == idx1 ? t1 : A.t[idx]
         lt2 = idx == idx2 ? t2 : A.t[idx + 1]
diff --git a/src/interpolation_methods.jl b/src/interpolation_methods.jl
index 334ce030..e00adc59 100644
--- a/src/interpolation_methods.jl
+++ b/src/interpolation_methods.jl
@@ -8,7 +8,7 @@ end
 function _interpolate(A::LinearInterpolation{<:AbstractVector}, t::Number, iguess)
     if isnan(t)
         # For correct derivative with NaN
-        idx = firstindex(A) - 1
+        idx = firstindex(A.u) - 1
         t1 = t2 = one(eltype(A.t))
         u1 = u2 = one(eltype(A.u))
     else