diff --git a/src/types/StateSpace.jl b/src/types/StateSpace.jl
index d1759fed8..937bbeaed 100644
--- a/src/types/StateSpace.jl
+++ b/src/types/StateSpace.jl
@@ -217,6 +217,8 @@ function isapprox(sys1::ST1, sys2::ST2; kwargs...) where {ST1<:AbstractStateSpac
 end
 
 ## ADDITION ##
+Base.zero(sys::AbstractStateSpace) = ss(zero(sys.D), sys.timeevol)
+
 function +(s1::StateSpace{TE,T}, s2::StateSpace{TE,T}) where {TE,T}
     #Ensure systems have same dimensions
     if size(s1) != size(s2)
diff --git a/src/types/TransferFunction.jl b/src/types/TransferFunction.jl
index 6695ba9bd..d02acb591 100644
--- a/src/types/TransferFunction.jl
+++ b/src/types/TransferFunction.jl
@@ -33,6 +33,8 @@ ninputs(G::TransferFunction) = size(G.matrix, 2)
 Base.ndims(::TransferFunction) = 2
 Base.size(G::TransferFunction) = size(G.matrix)
 Base.eltype(::Type{S}) where {S<:TransferFunction} = S
+Base.zero(G::TransferFunction{TE,S}) where {TE,S} = tf(zeros(numeric_type(S), size(G)), G.timeevol) # can not create a zero of a discrete system from the type alone, the sampletime is not stored.
+
 
 function Base.getindex(G::TransferFunction{TE,S}, inds...) where {TE,S<:SisoTf}
     if size(inds, 1) != 2
diff --git a/test/test_connections.jl b/test/test_connections.jl
index 9dcfccf37..fbc38dbb7 100644
--- a/test/test_connections.jl
+++ b/test/test_connections.jl
@@ -83,6 +83,15 @@ s = tf("s")
     vecarray(2, 1, [1,13,55,75], [1,13,55,75]));
 @test parallel(Ctf_111, Ctf_211) == tf([2,17,44,45], [1,13,55,75])
 
+# Test that the additive identity element for LTI system is known  
+@test zero(C_111) isa typeof(C_111)
+@test zero(Ctf_111) isa typeof(Ctf_111)
+@test zero(ss(randn(2,3))) == ss(zeros(2,3))
+@test zero(tf(randn(2,3))) == tf(zeros(2,3))
+
+
+
+    
 # Combination tf and ss
 @test [C_111 Ctf_221] == [C_111 ss(Ctf_221)]
 @test [C_111; Ctf_212] == [C_111; ss(Ctf_212)]