diff --git a/ext/LinearOperatorFFTWExt/DCTOp.jl b/ext/LinearOperatorFFTWExt/DCTOp.jl
index c415ddc..f8bf727 100644
--- a/ext/LinearOperatorFFTWExt/DCTOp.jl
+++ b/ext/LinearOperatorFFTWExt/DCTOp.jl
@@ -32,9 +32,9 @@ returns a `DCTOpImpl <: AbstractLinearOperator` which performs a DCT on a given
 * `shape::Tuple`  - size of the array to transform
 * `dcttype`       - type of DCT (currently `2` and `4` are supported)
 """
-function LinearOperatorCollection.DCTOp(T::Type; shape::Tuple, dcttype=2)
+function LinearOperatorCollection.DCTOp(T::Type; shape::Tuple, S = Array{T}, dcttype=2)
 
-  tmp=Array{T}(undef, shape) 
+  tmp=similar(S(undef, 0), shape...)
   if dcttype == 2
     plan = plan_dct!(tmp)
     iplan = plan_idct!(tmp)
diff --git a/ext/LinearOperatorFFTWExt/DSTOp.jl b/ext/LinearOperatorFFTWExt/DSTOp.jl
index f9c1955..b4b108e 100644
--- a/ext/LinearOperatorFFTWExt/DSTOp.jl
+++ b/ext/LinearOperatorFFTWExt/DSTOp.jl
@@ -31,8 +31,8 @@ returns a `LinearOperator` which performs a DST on a given input array.
 * `T::Type`       - type of the array to transform
 * `shape::Tuple`  - size of the array to transform
 """
-function LinearOperatorCollection.DSTOp(T::Type; shape::Tuple)
-  tmp=Array{T}(undef, shape)
+function LinearOperatorCollection.DSTOp(T::Type; shape::Tuple, S = Array{T})
+  tmp=similar(S(undef, 0), shape...)
 
   plan = FFTW.plan_r2r!(tmp,FFTW.RODFT10)
   iplan = FFTW.plan_r2r!(tmp,FFTW.RODFT01)