diff --git a/Project.toml b/Project.toml
index 8c5ef8275..4f541b494 100644
--- a/Project.toml
+++ b/Project.toml
@@ -4,6 +4,7 @@ authors = ["Joachim Brand <j.brand@massey.ac.nz>"]
 version = "0.9.1-dev"
 
 [deps]
+AllocCheck = "9b6a8646-10ed-4001-bbdc-1d2f46dfbb1a"
 Arrow = "69666777-d1a9-59fb-9406-91d4454c9d45"
 BSON = "fbb218c0-5317-5bc6-957e-2ee96dd4b1f0"
 Combinatorics = "861a8166-3701-5b0c-9a16-15d98fcdc6aa"
diff --git a/src/BitStringAddresses/BitStringAddresses.jl b/src/BitStringAddresses/BitStringAddresses.jl
index f139585d0..328de785e 100644
--- a/src/BitStringAddresses/BitStringAddresses.jl
+++ b/src/BitStringAddresses/BitStringAddresses.jl
@@ -9,6 +9,7 @@ using StaticArrays
 using SparseArrays
 using Setfield
 using Parameters
+using AllocCheck
 
 using Base.Cartesian
 
diff --git a/src/BitStringAddresses/occupationnumberfs.jl b/src/BitStringAddresses/occupationnumberfs.jl
index 8feaf7da1..91927bc90 100644
--- a/src/BitStringAddresses/occupationnumberfs.jl
+++ b/src/BitStringAddresses/occupationnumberfs.jl
@@ -133,7 +133,7 @@ See also: [`destroy`](@ref), [`excitation`](@ref).
     return (ofs, val)
 end
 
-"""
+@doc """
     excitation(addr::OccupationNumberFS, c::NTuple{<:Any,Int}, d::NTuple{<:Any,Int})
     → (nadd, α)
 Generate an excitation on an [`OccupationNumberFS`](@ref) by applying the creation and
@@ -158,7 +158,9 @@ julia> num_particles(es)
 7
 ```
 """
-function excitation(fs::OccupationNumberFS{<:Any, T}, c::NTuple{<:Any,Int}, d::NTuple{<:Any,Int}) where {T}
+excitation(fs::OccupationNumberFS{<:Any,T}, c::NTuple{<:Any,Int}, d::NTuple{<:Any,Int}) where {T}
+
+@check_allocs function excitation(fs::OccupationNumberFS{<:Any,T}, c::NTuple{<:Any,Int}, d::NTuple{<:Any,Int}) where {T}
     accu = one(T)
     for i in d
         fs, val = destroy(fs, i)
diff --git a/src/Hamiltonians/FroehlichPolaron.jl b/src/Hamiltonians/FroehlichPolaron.jl
index 940e92120..9a78ca0c9 100644
--- a/src/Hamiltonians/FroehlichPolaron.jl
+++ b/src/Hamiltonians/FroehlichPolaron.jl
@@ -24,12 +24,12 @@ geometry is to provide the number of dimensions `num_dimensions`. In this case t
 [`num_modes(address)`](@ref) of `address` must be a square number for `num_dimensions = 2`,
 or a cube number for `num_dimensions = 3`.
 
-The `address` must be of type [`ONRFS`](@ref).
+The `address` must be of type [`OccupationNumberFS`](@ref).
 """
 struct FroehlichPolaron{
     P, # total momentum
     T, # eltype
-    A<:ONRFS, # address type
+    A<:OccupationNumberFS, # address type
     G # lattice type
 } <: AbstractHamiltonian{T}
     add::A
@@ -40,7 +40,7 @@ struct FroehlichPolaron{
 end
 
 function FroehlichPolaron(
-    addr::ONRFS{<:Any, M};
+    addr::OccupationNumberFS{<:Any, M};
     geometry=nothing,
     alpha=1.0,
     total_mom=0.0,
@@ -91,7 +91,7 @@ Base.getproperty(h::FroehlichPolaron, ::Val{:geometry}) = getfield(h, :geometry)
 
 num_dimensions(h::FroehlichPolaron) = num_dimensions(h.geometry)
 
-# function diagonal_element(h::FroehlichPolaron, addr::ONRFS)
+# function diagonal_element(h::FroehlichPolaron, addr::OccupationNumberFS)
 #     return (
 #         (-h.total_mom)^2 +
 #         num_particles(addr) +