diff --git a/docs/src/lib/sets/Interval.md b/docs/src/lib/sets/Interval.md
index b8b175be3c..fad6557076 100644
--- a/docs/src/lib/sets/Interval.md
+++ b/docs/src/lib/sets/Interval.md
@@ -23,7 +23,6 @@ dim(::Interval)
 σ(::AbstractVector, ::Interval)
 ρ(::AbstractVector, ::Interval)
 ∈(::AbstractVector, ::Interval)
-∈(::Number, ::Interval)
 an_element(::Interval)
 vertices_list(::Interval)
 translate(::Interval, ::AbstractVector)
diff --git a/src/Sets/Interval/in.jl b/src/Sets/Interval/in.jl
index a4506d70fd..22b59f4d25 100644
--- a/src/Sets/Interval/in.jl
+++ b/src/Sets/Interval/in.jl
@@ -17,21 +17,3 @@ function ∈(v::AbstractVector, x::Interval)
                            "incompatible with an interval"
     return @inbounds v[1] ∈ x.dat
 end
-
-"""
-    ∈(v::Number, x::Interval)
-
-Check whether a number is contained in an interval.
-
-### Input
-
-- `v` -- scalar
-- `x` -- interval
-
-### Output
-
-`true` iff `x` contains the singleton `[v]`.
-"""
-function ∈(v::Number, x::Interval)
-    return v ∈ x.dat
-end
diff --git a/test/Sets/BallInf.jl b/test/Sets/BallInf.jl
index 45cfe13dac..5b4df4443f 100644
--- a/test/Sets/BallInf.jl
+++ b/test/Sets/BallInf.jl
@@ -70,7 +70,7 @@ for N in [Float64, Rational{Int}, Float32]
 
     # support vector for single entry vector
     svec = σ(SingleEntryVector(2, 3, N(2)), BallInf(zeros(N, 3), N(2)))
-    @test svec[1] ∈ Interval(N[-2, 2]) && svec[2] == N(2) && svec[3] ∈ Interval(N[-2, 2])
+    @test -2 <= svec[1] <= 2 && svec[2] == N(2) && -2 <= svec[3] <= 2
 
     # support function
     B = BallInf(N[1, 2], N(1))
diff --git a/test/Sets/Interval.jl b/test/Sets/Interval.jl
index a110993ef4..0ee2eb55bc 100644
--- a/test/Sets/Interval.jl
+++ b/test/Sets/Interval.jl
@@ -37,6 +37,8 @@ for N in [Float64, Float32, Rational{Int}]
 
     # test interface method an_element and membership
     @test an_element(x) ∈ x
+    # number in interval is invalid
+    @test_throws MethodError N(1) ∈ x
     # test containment
     @test x ⊆ x
     @test x ⊈ N(0.2) * x