diff --git a/Project.toml b/Project.toml
index 08c50b952..3aa9a0ea2 100644
--- a/Project.toml
+++ b/Project.toml
@@ -1,7 +1,7 @@
 name = "IntervalArithmetic"
 uuid = "d1acc4aa-44c8-5952-acd4-ba5d80a2a253"
 repo = "https://github.com/JuliaIntervals/IntervalArithmetic.jl.git"
-version = "0.20.5"
+version = "0.20.6"
 
 [deps]
 CRlibm = "96374032-68de-5a5b-8d9e-752f78720389"
diff --git a/src/multidim/intervalbox.jl b/src/multidim/intervalbox.jl
index 0b0e7da85..9052bd30a 100644
--- a/src/multidim/intervalbox.jl
+++ b/src/multidim/intervalbox.jl
@@ -82,6 +82,11 @@ end
 ∈(X::AbstractVector, Y::IntervalBox{N, T}) where {N, T} = all(X .∈ Y)
 ∈(X, Y::IntervalBox{N, T}) where {N, T} = throw(ArgumentError("$X ∈ $Y is not defined"))
 
+# mixing intervals with one-dimensional interval boxes
+for op in (:⊆, :⊂, :⊃, :∩, :∪)
+    @eval $(op)(a::Interval, X::IntervalBox{1}) = $(op)(a, first(X))
+    @eval $(op)(X::IntervalBox{1}, a::Interval) = $(op)(first(X), a)
+end
 
 #=
 On Julia 0.6 can now write
diff --git a/test/multidim_tests/multidim.jl b/test/multidim_tests/multidim.jl
index 89a32ac0c..1117caa3e 100644
--- a/test/multidim_tests/multidim.jl
+++ b/test/multidim_tests/multidim.jl
@@ -68,6 +68,13 @@ let X, A  # avoid problems with global variables
         @test A ∪ B.v ≛ B
     end
 
+    x = 0.5 .. 3
+    a = IntervalBox(A[1]) # 1 .. 2
+    @test !(x ⊆ a) && a ⊆ x
+    @test !(x ⊂ a) && a ⊂ x
+    @test x ∩ a == a ∩ x == A[1]
+    @test x ∪ a ==  a ∪ x == x
+
     X = IntervalBox(1..2, 3..4)
     Y = IntervalBox(3..4, 3..4)
 
@@ -333,7 +340,7 @@ end
     @test hull(vb3...) ≛ ib3
     @test hull(vb3) ≛ ib3
     @test all(mince(ib3, (4,4,4)) .≛ vb3)
-    @test all(mince(ib3, (2,1,1)) .≛ [(-1 .. 0)×(-1 .. 1)×(-1 .. 1), 
+    @test all(mince(ib3, (2,1,1)) .≛ [(-1 .. 0)×(-1 .. 1)×(-1 .. 1),
         (0 .. 1)×(-1 .. 1)×(-1 .. 1)])
     @test hull(mince(ib3, (2,1,1))) ≛ ib3