diff --git a/src/Hamiltonians/reduced_density_matrix.jl b/src/Hamiltonians/reduced_density_matrix.jl
index 3f5a75444..1bfbe32cf 100644
--- a/src/Hamiltonians/reduced_density_matrix.jl
+++ b/src/Hamiltonians/reduced_density_matrix.jl
@@ -196,7 +196,7 @@ LOStructure(::Type{<:ReducedDensityMatrix}) = IsHermitian()
 function Interfaces.dot_from_right(
     left::AbstractDVec, op::ReducedDensityMatrix{P}, right::AbstractDVec
 ) where {P}
-    if (keytype(left) <: BoseFS && P > 1)
+    if (keytype(left) <: BoseFS && isless(1,P))
          ArgumentError("ReducedDensityMatrix(<:BoseFS, p > 1) is not measurable")
     end
     dim = binomial(num_modes(keytype(left)), P)