diff --git a/Project.toml b/Project.toml
index 68e3100..ee8ccda 100644
--- a/Project.toml
+++ b/Project.toml
@@ -1,6 +1,6 @@
 name = "BlockTensorKit"
 uuid = "5f87ffc2-9cf1-4a46-8172-465d160bd8cd"
-version = "0.3.12"
+version = "0.3.13"
 authors = ["Lukas Devos <ldevos98@gmail.com> and contributors"]
 
 [deps]
diff --git a/src/tensors/blocktensor.jl b/src/tensors/blocktensor.jl
index 33e4765..3d2b6d9 100644
--- a/src/tensors/blocktensor.jl
+++ b/src/tensors/blocktensor.jl
@@ -164,7 +164,7 @@ Base.parent(t::BlockTensorMap) = t.data
 # handle this separately because the storagetype of `AbstractTensorMap` is
 # *always* Vector no matter the actual data storage type
 TK.storagetype(t::BlockTensorMap{AbstractTensorMap{E, S, N₁, N₂}}) where {E, S, N₁, N₂} =
-    foldl(TK.promote_storagetype, values(t.data))
+    mapreduce(TK.storagetype, TK.promote_storagetype, values(t.data); init = TK.storagetype(eltype(t)))
 
 function Base.copyto!(
         dest::BlockTensorMap, Rdest::CartesianIndices,
diff --git a/src/tensors/sparseblocktensor.jl b/src/tensors/sparseblocktensor.jl
index a818f03..d919caf 100644
--- a/src/tensors/sparseblocktensor.jl
+++ b/src/tensors/sparseblocktensor.jl
@@ -171,7 +171,7 @@ Base.eltype(::Type{<:SparseBlockTensorMap{TT}}) where {TT} = TT
 # handle this separately because the storagetype of `AbstractTensorMap` is
 # *always* Vector no matter the actual data storage type
 TK.storagetype(t::SparseBlockTensorMap{AbstractTensorMap{E, S, N₁, N₂}}) where {E, S, N₁, N₂} =
-    foldl(TK.promote_storagetype, nonzero_values(t))
+    mapreduce(TK.storagetype, TK.promote_storagetype, nonzero_values(t); init = TK.storagetype(eltype(t)))
 
 issparse(::SparseBlockTensorMap) = true
 nonzero_keys(t::SparseBlockTensorMap) = keys(t.data)