diff --git a/src/abstractNFFTs.jl b/src/abstractNFFTs.jl
index 4a07d1a..3c20cdd 100644
--- a/src/abstractNFFTs.jl
+++ b/src/abstractNFFTs.jl
@@ -91,7 +91,7 @@ Base.@constprop :aggressive function PlanNUFFT(
     m, σ, reltol = AbstractNFFTs.accuracyParams(; kwargs...)
     backend = KA.get_backend(xp)  # e.g. use GPU backend if xp is a GPU array
     sort_points = sortNodes ? True() : False()  # this is type-unstable (unless constant propagation happens)
-    block_size = blocking ? default_block_size() : nothing  # also type-unstable
+    block_size = blocking ? default_block_size(backend) : nothing  # also type-unstable
     kernel = window isa AbstractKernel ? window : convert_window_function(window)
     p = PlanNUFFT(Complex{Tr}, Ns, HalfSupport(m); backend, σ = Tr(σ), sort_points, fftshift, block_size, kernel, fftw_flags = fftflags)
     AbstractNFFTs.nodes!(p, xp)
diff --git a/test/accuracy.jl b/test/accuracy.jl
index 2aec8cc..cc83fcb 100644
--- a/test/accuracy.jl
+++ b/test/accuracy.jl
@@ -95,7 +95,7 @@ function test_nufft_type1_1d(
         Np = 2 * N,
         m = HalfSupport(8),
         σ = 1.25,
-        block_size = NonuniformFFTs.default_block_size(),
+        block_size = NonuniformFFTs.default_block_size(CPU()),
     ) where {T <: Number}
     if T <: Real
         Tr = T
@@ -154,7 +154,7 @@ function test_nufft_type2_1d(
         Np = 2 * N,
         m = HalfSupport(8),
         σ = 1.25,
-        block_size = NonuniformFFTs.default_block_size(),
+        block_size = NonuniformFFTs.default_block_size(CPU()),
     ) where {T <: Number}
     if T <: Real
         Tr = T
diff --git a/test/multidimensional.jl b/test/multidimensional.jl
index e4c1b83..4ead8f1 100644
--- a/test/multidimensional.jl
+++ b/test/multidimensional.jl
@@ -32,7 +32,7 @@ function test_nufft_type1(
         Np = 2 * first(Ns),
         m = HalfSupport(8),
         σ = 1.25,
-        block_size = NonuniformFFTs.default_block_size(),
+        block_size = NonuniformFFTs.default_block_size(CPU()),
         sort_points = False(),
     ) where {T <: Number}
     Tr = real(T)
@@ -79,7 +79,7 @@ function test_nufft_type2(
         Np = 2 * first(Ns),
         m = HalfSupport(8),
         σ = 1.25,
-        block_size = NonuniformFFTs.default_block_size(),
+        block_size = NonuniformFFTs.default_block_size(CPU()),
         sort_points = False(),
     ) where {T <: Number}
     Tr = real(T)