diff --git a/modules/environment/ca.nix b/modules/environment/ca.nix
new file mode 100644
index 0000000..09b6417
--- /dev/null
+++ b/modules/environment/ca.nix
@@ -0,0 +1,37 @@
+# Copyright (c) 2019-2021, see AUTHORS. Licensed under MIT License, see LICENSE.
+
+{ config, lib, pkgs, ... }:
+
+with lib;
+
+let
+  certificate = "${pkgs.cacert}/etc/ssl/certs/ca-bundle.crt";
+in
+
+{
+
+  ###### interface
+
+  options = {
+
+  };
+
+
+  ###### implementation
+
+  config = {
+
+    environment.etc = {
+      # NixOS canonical location + Debian/Ubuntu/Arch/Gentoo compatibility.
+      "ssl/certs/ca-certificates.crt".source = certificate;
+
+      # Old NixOS compatibility.
+      "ssl/certs/ca-bundle.crt".source = certificate;
+
+      # CentOS/Fedora compatibility.
+      "pki/tls/certs/ca-bundle.crt".source = certificate;
+    };
+
+  };
+
+}
diff --git a/modules/module-list.nix b/modules/module-list.nix
index cbac88f..f35eec1 100644
--- a/modules/module-list.nix
+++ b/modules/module-list.nix
@@ -5,6 +5,7 @@
 [
   ./build/activation.nix
   ./build/config.nix
+  ./environment/ca.nix
   ./environment/etc
   ./environment/links.nix
   ./environment/login