diff --git a/Project.toml b/Project.toml
index 70606a63..9f4fdae6 100644
--- a/Project.toml
+++ b/Project.toml
@@ -5,13 +5,24 @@ repo = "https://github.com/JuliaAlgebra/MultivariatePolynomials.jl"
 version = "0.5.12"
 
 [deps]
-ChainRulesCore = "d360d2e6-b24c-11e9-a2a3-2a2ae2dbcce4"
 DataStructures = "864edb3b-99cc-5e75-8d2d-829cb0a9cfe8"
 LinearAlgebra = "37e2e46d-f89d-539d-b4ee-838fcccc9c8e"
 MutableArithmetics = "d8a4904e-b15c-11e9-3269-09a3773c0cb0"
 
+[weakdeps]
+ChainRulesCore = "d360d2e6-b24c-11e9-a2a3-2a2ae2dbcce4"
+
+[extensions]
+MultivariatePolynomialsChainRulesCoreExt = "ChainRulesCore"
+
 [compat]
 ChainRulesCore = "1"
 DataStructures = "0.19"
 MutableArithmetics = "0.3, 1"
 julia = "1.10"
+
+[extras]
+ChainRulesCore = "d360d2e6-b24c-11e9-a2a3-2a2ae2dbcce4"
+
+[targets]
+test = ["ChainRulesCore"]
diff --git a/src/chain_rules.jl b/ext/MultivariatePolynomialsChainRulesCoreExt.jl
similarity index 90%
rename from src/chain_rules.jl
rename to ext/MultivariatePolynomialsChainRulesCoreExt.jl
index 77fe609a..96b51a8e 100644
--- a/src/chain_rules.jl
+++ b/ext/MultivariatePolynomialsChainRulesCoreExt.jl
@@ -1,4 +1,8 @@
+module MultivariatePolynomialsChainRulesCoreExt
+
 import ChainRulesCore
+using MultivariatePolynomials
+using MultivariatePolynomials: _APL, MA
 
 ChainRulesCore.@scalar_rule +(x::_APL) true
 ChainRulesCore.@scalar_rule -(x::_APL) -1
@@ -30,3 +34,5 @@ function ChainRulesCore.rrule(::typeof(differentiate), p, x)
     dpdx = differentiate(p, x)
     return dpdx, Base.Fix2(pullback, x)
 end
+
+end
diff --git a/src/MultivariatePolynomials.jl b/src/MultivariatePolynomials.jl
index 9de4709e..988b3552 100644
--- a/src/MultivariatePolynomials.jl
+++ b/src/MultivariatePolynomials.jl
@@ -86,7 +86,6 @@ include("antidifferentiation.jl")
 include("division.jl")
 include("gcd.jl")
 include("det.jl")
-include("chain_rules.jl")
 
 include("default_term.jl")
 include("sequences.jl")