diff --git a/Project.toml b/Project.toml
index 6499f65..0adb7f2 100644
--- a/Project.toml
+++ b/Project.toml
@@ -1,6 +1,6 @@
 name = "ITensorBase"
 uuid = "4795dd04-0d67-49bb-8f44-b89c448a1dc7"
-version = "0.13.0"
+version = "0.13.1"
 authors = ["ITensor developers <support@itensor.org> and contributors"]
 
 [workspace]
diff --git a/src/abstractnamedtensor.jl b/src/abstractnamedtensor.jl
index ff3a9a0..8ed058b 100644
--- a/src/abstractnamedtensor.jl
+++ b/src/abstractnamedtensor.jl
@@ -79,7 +79,8 @@ Symbol
 """
 function dimnametype end
 dimnametype(a::AbstractNamedTensor) = dimnametype(typeof(a))
-dimnametype(type::Type{<:AbstractNamedTensor}) = Any
+dimnametype(::Type{<:AbstractNamedTensor{DimName}}) where {DimName} = DimName
+dimnametype(::Type{<:AbstractNamedTensor}) = Any
 
 # Unwrapping the names (named-array interface).
 # TODO: Use `IsNamed` trait?
diff --git a/src/lazyitensors/symbolicitensor.jl b/src/lazyitensors/symbolicitensor.jl
index cc6ebad..6ea2f2b 100644
--- a/src/lazyitensors/symbolicitensor.jl
+++ b/src/lazyitensors/symbolicitensor.jl
@@ -23,7 +23,6 @@ dimnames(a::SymbolicNamedTensor) = getfield(a, :dimnames)
 function Base.axes(a::SymbolicNamedTensor)
     return named.(Tuple(Base.OneTo.(getfield(a, :size))), Tuple(getfield(a, :dimnames)))
 end
-dimnametype(::Type{<:SymbolicNamedTensor{DimName}}) where {DimName} = DimName
 Base.ndims(a::SymbolicNamedTensor) = length(getfield(a, :dimnames))
 
 function Base.:(==)(a::SymbolicNamedTensor, b::SymbolicNamedTensor)
diff --git a/src/namedtensor.jl b/src/namedtensor.jl
index dbba7ea..c8ad977 100644
--- a/src/namedtensor.jl
+++ b/src/namedtensor.jl
@@ -69,8 +69,6 @@ dimnames(a::NamedTensor) = a.dimnames
 unnamed(a::NamedTensor) = a.unnamed
 Base.parent(a::NamedTensor) = unnamed(a)
 
-dimnametype(::Type{<:NamedTensor{DimName}}) where {DimName} = DimName
-
 # The parent array is erased at the field level, so its concrete type is not part
 # of `NamedTensor`'s signature. An instance still carries the parent, so the instance
 # methods recover the concrete type while the type methods report `AbstractArray`.
diff --git a/test/test_basics.jl b/test/test_basics.jl
index 834a994..3d69f5f 100644
--- a/test/test_basics.jl
+++ b/test/test_basics.jl
@@ -1,8 +1,8 @@
 using ITensorBase: ITensorBase, AbstractNamedTensor, ITensor, Index, IndexName, NamedTensor,
     commonind, commoninds, dimnametype, gettag, hascommoninds, hastag, id, inds, mapinds,
-    name, named, noncommonind, noncommoninds, noprime, plev, prime, replaceinds, setplev,
-    settag, sim, tags, trycommonind, trynoncommonind, tryuniqueind, unioninds, uniqueind,
-    uniqueinds, uniquename, unname, unnamed, unsettag, uuid
+    name, named, noncommonind, noncommoninds, noprime, operator, plev, prime, replaceinds,
+    setplev, settag, sim, tags, trycommonind, trynoncommonind, tryuniqueind, unioninds,
+    uniqueind, uniqueinds, uniquename, unname, unnamed, unsettag, uuid
 using Test: @test, @test_broken, @test_throws, @testset
 using UUIDs: UUID
 
@@ -172,6 +172,10 @@ using UUIDs: UUID
         @test dimnametype(a) === IndexName
         @test dimnametype(typeof(a)) === IndexName
         @test dimnametype(NamedTensor{IndexName}) === IndexName
+        # An operator reports the dimname flavor of its underlying tensor.
+        op = operator(a, (name(i),), (name(j),))
+        @test dimnametype(op) === IndexName
+        @test dimnametype(typeof(op)) === IndexName
         # Unparameterized `NamedTensor` does not fix its dimname flavor, like `eltype(Array)`.
         @test dimnametype(NamedTensor) === Any
     end