diff --git a/src/LogarithmicNumbers.jl b/src/LogarithmicNumbers.jl
index 42902ce..b1f8190 100644
--- a/src/LogarithmicNumbers.jl
+++ b/src/LogarithmicNumbers.jl
@@ -328,6 +328,10 @@ function Base.isequal(x::Logarithmic, y::Logarithmic)
     isequal(x.abs, y.abs) && isequal(x.signbit, y.signbit)
 end
 
+function Base.isapprox(x::ULogarithmic, y::ULogarithmic; kwargs...)
+    isapprox(Logarithmic(x), Logarithmic(y); kwargs...)
+end
+
 function Base.:(<)(x::ULogarithmic, y::ULogarithmic)
     x.log < y.log
 end
diff --git a/test/runtests.jl b/test/runtests.jl
index 4e2a53e..ee9561e 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -305,6 +305,16 @@ atypes2 = (ULogarithmic, ULogFloat32, Logarithmic, LogFloat32)
             end
         end
 
+        @testset "isapprox" begin
+            for A in atypes, x1 in vals
+                A <: ULogarithmic && x1 < 0 && continue
+                x2 = x1 + 1e-12
+                y1 = A(x1)
+                y2 = A(x2)
+                @test @inferred(isapprox(y1, y2; atol=1e-11)) == isapprox(x1,x2; atol=1e-11)
+            end
+        end
+
         @testset "<" begin
             for A in atypes, x1 in vals, x2 in vals
                 A <: ULogarithmic && (x1 < 0 || x2 < 0) && continue