diff --git a/src/algorithms/groundstate/find_groundstate.jl b/src/algorithms/groundstate/find_groundstate.jl
index 30a5abcfd..493dbdc45 100644
--- a/src/algorithms/groundstate/find_groundstate.jl
+++ b/src/algorithms/groundstate/find_groundstate.jl
@@ -26,7 +26,7 @@ function find_groundstate(
         tol = Defaults.tol, maxiter = Defaults.maxiter,
         verbosity = Defaults.verbosity, trscheme = nothing
     )
-    if isa(ψ, InfiniteMPS)
+    if GeometryStyle(ψ) == InfiniteChainStyle()
         alg = VUMPS(; tol = max(1.0e-4, tol), verbosity, maxiter)
         if tol < 1.0e-4
             alg = alg & GradientGrassmann(; tol = tol, maxiter, verbosity)
@@ -34,7 +34,7 @@ function find_groundstate(
         if !isnothing(trscheme)
             alg = IDMRG2(; tol = min(1.0e-2, 100tol), verbosity, trscheme) & alg
         end
-    elseif isa(ψ, AbstractFiniteMPS)
+    elseif GeometryStyle(ψ) == FiniteChainStyle()
         alg = DMRG(; tol, maxiter, verbosity)
         if !isnothing(trscheme)
             alg = DMRG2(; tol = min(1.0e-2, 100tol), verbosity, trscheme) & alg
diff --git a/src/algorithms/groundstate/idmrg.jl b/src/algorithms/groundstate/idmrg.jl
index 6cb71afd3..801b868c4 100644
--- a/src/algorithms/groundstate/idmrg.jl
+++ b/src/algorithms/groundstate/idmrg.jl
@@ -72,6 +72,7 @@ end
 
 function find_groundstate(mps, operator, alg::alg_type, envs = environments(mps, operator)) where {alg_type <: Union{<:IDMRG, <:IDMRG2}}
     (length(mps) ≤ 1 && alg isa IDMRG2) && throw(ArgumentError("unit cell should be >= 2"))
+    GeometryStyle(operator, mps) != InfiniteChainStyle() && throw(ArgumentError("IDMRG only supports infinite systems."))
     log = alg isa IDMRG ? IterLog("IDMRG") : IterLog("IDMRG2")
     mps = copy(mps)
     iter = 0
diff --git a/src/algorithms/groundstate/vumps.jl b/src/algorithms/groundstate/vumps.jl
index 99da8234c..5199b4ad4 100644
--- a/src/algorithms/groundstate/vumps.jl
+++ b/src/algorithms/groundstate/vumps.jl
@@ -46,7 +46,7 @@ struct VUMPSState{S, O, E}
 end
 
 function find_groundstate(
-        mps::InfiniteMPS, operator, alg::VUMPS, envs = environments(mps, operator)
+        mps, operator, alg::VUMPS, envs = environments(mps, operator)
     )
     return dominant_eigsolve(operator, mps, alg, envs; which = :SR)
 end
@@ -55,6 +55,7 @@ function dominant_eigsolve(
         operator, mps, alg::VUMPS, envs = environments(mps, operator);
         which
     )
+    GeometryStyle(operator, mps) != InfiniteChainStyle() && throw(ArgumentError("VUMPS only supports infinite systems."))
     log = IterLog("VUMPS")
     iter = 0
     ϵ = calc_galerkin(mps, operator, mps, envs)
diff --git a/src/operators/lazysum.jl b/src/operators/lazysum.jl
index 7bb2b5ce8..366a221d7 100644
--- a/src/operators/lazysum.jl
+++ b/src/operators/lazysum.jl
@@ -30,6 +30,9 @@ Base.complex(x::LazySum) = LazySum(complex.(x.ops))
 TimeDependence(x::LazySum) = istimed(x) ? TimeDependent() : NotTimeDependent()
 istimed(x::LazySum) = any(istimed, x)
 
+OperatorStyle(::Type{LazySum{O}}) where {O} = OperatorStyle(O)
+GeometryStyle(::Type{LazySum{O}}) where {O} = GeometryStyle(O)
+
 # constructors
 LazySum(x) = LazySum([x])
 LazySum(ops::AbstractVector, fs::AbstractVector) = LazySum(map(MultipliedOperator, ops, fs))