diff --git a/Project.toml b/Project.toml
index 7b4d0bd..3a8ad29 100644
--- a/Project.toml
+++ b/Project.toml
@@ -1,7 +1,7 @@
 name = "IrrationalConstants"
 uuid = "92d709cd-6900-40b7-9082-c6be49f344b6"
 authors = ["JuliaMath"]
-version = "0.2.3"
+version = "0.2.4"
 
 [compat]
 julia = "1"
diff --git a/src/macro.jl b/src/macro.jl
index 0dc5056..12a66bc 100644
--- a/src/macro.jl
+++ b/src/macro.jl
@@ -135,5 +135,32 @@ function irrational(sym::Symbol, val::Union{Float64,Expr}, def::Union{Symbol,Exp
         @assert isa(big($esym), BigFloat)
         @assert Float64($esym) == Float64(big($esym))
         @assert Float32($esym) == Float32(big($esym))
+
+        # https://github.com/JuliaLang/julia/pull/55886 removed these effects for generic `AbstractIrrational` subtypes
+        @static if isdefined(Base, :_throw_argument_error_irrational_to_rational_bigint)
+            function Base.Rational{$BigInt}(::$eT)
+                Base._throw_argument_error_irrational_to_rational_bigint()
+            end
+        end
+        @static if isdefined(Base, :_irrational_to_rational)
+            Base.@assume_effects :foldable function Base.Rational{T}(x::$eT) where {T<:Integer}
+                Base._irrational_to_rational(T, x)
+            end
+        end
+        @static if isdefined(Base, :_irrational_to_float)
+            Base.@assume_effects :foldable function (::Type{T})(x::$eT, r::RoundingMode) where {T<:Union{Float32,Float64}}
+                Base._irrational_to_float(T, x, r)
+            end
+        end
+        @static if isdefined(Base, :_rationalize_irrational)
+            Base.@assume_effects :foldable function Base.rationalize(::Type{T}, x::$eT; tol::Real=0) where {T<:Integer}
+                Base._rationalize_irrational(T, x, tol)
+            end
+        end
+        @static if isdefined(Base, :_lessrational)
+            Base.@assume_effects :foldable function Base.lessrational(rx::Rational, x::$eT)
+                Base._lessrational(rx, x)
+            end
+        end
     end
 end
diff --git a/test/runtests.jl b/test/runtests.jl
index d9a8bca..4ac2b8e 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -255,3 +255,8 @@ end
         )
     end
 end
+
+# issues #37 and #40
+@testset "slow comparisons" begin
+    @test iszero(@allocated(3.0 <= invsqrt2))
+end