diff --git a/Project.toml b/Project.toml
index 79154e8..1dc7125 100644
--- a/Project.toml
+++ b/Project.toml
@@ -1,7 +1,7 @@
 name = "Infinities"
 uuid = "e1ba4f0e-776d-440f-acd9-e1d2e9742647"
 authors = ["Sheehan Olver <solver@mac.com>"]
-version = "0.1.8"
+version = "0.1.9"
 
 [compat]
 Aqua = "0.8"
diff --git a/src/Infinities.jl b/src/Infinities.jl
index 0eee1f8..1706a27 100644
--- a/src/Infinities.jl
+++ b/src/Infinities.jl
@@ -68,6 +68,8 @@ angle(x::RealInfinity) = π*signbit(x)
 string(y::RealInfinity) = signbit(y) ? "-∞" : "+∞"
 show(io::IO, y::RealInfinity) = print(io, string(y))
 
+Base.to_index(i::RealInfinity) = convert(Integer, i)
+
 #######
 # ComplexInfinity
 #######
diff --git a/test/runtests.jl b/test/runtests.jl
index 5922f4e..84ee6eb 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -203,6 +203,8 @@ using Aqua
             @test convert(Float16, -∞) ≡ Float16(-∞) ≡ -Inf16
             @test convert(BigFloat, -∞)::BigFloat == BigFloat(-∞)::BigFloat == -BigFloat(Inf)
         end
+
+        @test Base.to_index(RealInfinity()) ≡ ℵ₀
     end
 
     @testset "ComplexInfinity" begin