diff --git a/.github/workflows/CI.yml b/.github/workflows/CI.yml
index 82708b4..6f24586 100644
--- a/.github/workflows/CI.yml
+++ b/.github/workflows/CI.yml
@@ -28,7 +28,6 @@ jobs:
           - '4.15'
           - '4.14'
           - '4.13'
-          - '4.12'
 
     steps:
       - uses: actions/checkout@v6
diff --git a/PackageInfo.g b/PackageInfo.g
index bf4ceb1..d12e847 100644
--- a/PackageInfo.g
+++ b/PackageInfo.g
@@ -74,13 +74,20 @@ PackageDoc := rec(
 ),
 
 Dependencies := rec(
-  GAP := ">= 4.12",
+  GAP := ">= 4.13",
   NeededOtherPackages := [ [ "GAPDoc", ">= 1.5" ] ],
   SuggestedOtherPackages := [ ],
   NeededSystemPackages := rec( Ubuntu := [["libcdd-dev"]], Homebrew := [["cddlib"]] ),
   ExternalConditions := [ ],
 ),
 
+Extensions := [
+  rec(
+    needed := [ [ "JuliaInterface", ">= 0.2" ], [ "ToolsForHomalg", ">= 2020.05.12" ] ],
+    filename := "gap/Julia.g",
+  ),
+],
+
 AvailabilityTest :=
   function()
     if not IsKernelExtensionAvailable("CddInterface") then
diff --git a/gap/Julia.g b/gap/Julia.g
new file mode 100644
index 0000000..27af09f
--- /dev/null
+++ b/gap/Julia.g
@@ -0,0 +1,8 @@
+#
+# CddInterface: Gap interface to Cdd package
+#
+# Package extension, read by GAP once JuliaInterface and ToolsForHomalg
+# are loaded.
+#
+ReadPackage( "CddInterface", "gap/Julia.gd");
+ReadPackage( "CddInterface", "gap/Julia.gi");
diff --git a/init.g b/init.g
index 6cca5da..63aebf2 100644
--- a/init.g
+++ b/init.g
@@ -10,8 +10,3 @@ fi;
 
 ReadPackage( "CddInterface", "gap/polyhedra.gd");
 ReadPackage( "CddInterface", "gap/tools.gd");
-
-if IsPackageMarkedForLoading( "JuliaInterface", ">= 0.2" ) and
-   IsPackageMarkedForLoading( "ToolsForHomalg", ">= 2020.05.12" ) then
-    ReadPackage( "CddInterface", "gap/Julia.gd");
-fi;
diff --git a/read.g b/read.g
index 1ecc139..7db6ae9 100644
--- a/read.g
+++ b/read.g
@@ -5,8 +5,3 @@
 #
 ReadPackage( "CddInterface", "gap/polyhedra.gi");
 ReadPackage( "CddInterface", "gap/tools.gi");
-
-if IsPackageMarkedForLoading( "JuliaInterface", ">= 0.2" ) and
-   IsPackageMarkedForLoading( "ToolsForHomalg", ">= 2020.05.12" ) then
-    ReadPackage( "CddInterface", "gap/Julia.gi");
-fi;