diff --git a/lib/ControlSystemsBase/src/matrix_comps.jl b/lib/ControlSystemsBase/src/matrix_comps.jl
index b216d8473..67f42a4bc 100644
--- a/lib/ControlSystemsBase/src/matrix_comps.jl
+++ b/lib/ControlSystemsBase/src/matrix_comps.jl
@@ -474,7 +474,7 @@ function _infnorm_two_steps_dt(sys::AbstractStateSpace, normtype::Symbol, tol=1e
     on_unit_circle = z -> abs(abs(z) - 1) < approxcirc # Helper fcn for readability
 
     T = promote_type(real(numeric_type(sys)), Float64, typeof(true/sys.Ts))
-    Tw = typeof(one(T)/sys.Ts)
+    Tw = typeof(oneunit(T)/sys.Ts)
 
     if sys.nx == 0  # static gain
         return (T(opnorm(sys.D)), Tw(0))
diff --git a/lib/ControlSystemsBase/src/types/SisoTfTypes/SisoRational.jl b/lib/ControlSystemsBase/src/types/SisoTfTypes/SisoRational.jl
index 6fca28bbb..87643556d 100644
--- a/lib/ControlSystemsBase/src/types/SisoTfTypes/SisoRational.jl
+++ b/lib/ControlSystemsBase/src/types/SisoTfTypes/SisoRational.jl
@@ -39,7 +39,7 @@ Base.zero(f::SisoRational) = zero(typeof(f))
 isproper(f::SisoRational) = (length(f.num) <= length(f.den))
 
 function minreal(sys::SisoRational{T}, eps::Real=sqrt(eps())) where T
-    T2 = typeof(zero(T)/one(T))
+    T2 = typeof(oneunit(T)/oneunit(T))
     return convert(SisoRational{T2}, minreal(convert(SisoZpk,sys), eps))
 end
 
diff --git a/lib/ControlSystemsBase/src/types/conversion.jl b/lib/ControlSystemsBase/src/types/conversion.jl
index 075482c29..b01990997 100644
--- a/lib/ControlSystemsBase/src/types/conversion.jl
+++ b/lib/ControlSystemsBase/src/types/conversion.jl
@@ -291,7 +291,7 @@ function convert(::Type{TransferFunction{TE,SisoRational{T}}}, sys::AbstractStat
     TransferFunction{TE,SisoRational{T}}(matrix, TE(sys.timeevol))
 end
 function convert(::Type{TransferFunction{TE1,SisoRational}}, sys::StateSpace{TE2,T0}) where {TE1,TE2,T0<:Number}
-    T = typeof(one(T0)/one(T0))
+    T = typeof(oneunit(T0)/oneunit(T0))
     convert(TransferFunction{TE1,SisoRational{T}}, sys)
 end
 
@@ -307,7 +307,7 @@ function convert(::Type{TransferFunction{TE,SisoZpk{T,TR}}}, sys::AbstractStateS
 end
 function convert(::Type{TransferFunction{TE1,SisoZpk}}, sys::AbstractStateSpace{TE2}) where {TE1,TE2}
     T0 = numeric_type(sys)
-    T = typeof(one(T0)/one(T0))
+    T = typeof(oneunit(T0)/oneunit(T0))
     convert(TransferFunction{TE1,SisoZpk{T,complex(T)}}, sys)
 end
 
@@ -335,7 +335,7 @@ Implements: "An accurate and efficient algorithm for the computation of the char
 """
 function charpoly(A::AbstractMatrix{T}) where {T}
     N = size(A, 1)
-    TT = typeof(one(T)/one(T))
+    TT = typeof(oneunit(T)/oneunit(T))
     poly_factors = vec(ones(TT, N+1))
     if N <= 0
         return poly_factors
diff --git a/lib/ControlSystemsBase/src/types/zpk.jl b/lib/ControlSystemsBase/src/types/zpk.jl
index 50bb77bcc..f225da5a7 100644
--- a/lib/ControlSystemsBase/src/types/zpk.jl
+++ b/lib/ControlSystemsBase/src/types/zpk.jl
@@ -65,7 +65,7 @@ zpk(k::Real, Ts::TimeEvolution) = zpk(eltype(k)[], eltype(k)[], k, Ts)
 zpk(sys::AbstractStateSpace) = zpk(zpkdata(sys)..., timeevol(sys))
 
 function zpk(G::TransferFunction{TE,S}) where {TE<:TimeEvolution,T0, S<:SisoTf{T0}}
-    T = typeof(one(T0)/one(T0))
+    T = typeof(oneunit(T0)/oneunit(T0))
     convert(TransferFunction{TE,SisoZpk{T, complex(T)}}, G)
 end