diff --git a/common/common.nix b/common/common.nix
index f7bd3e3..a1fe580 100644
--- a/common/common.nix
+++ b/common/common.nix
@@ -77,7 +77,7 @@
   # this value at the release version of the first install of this system.
   # Before changing this value read the documentation for this option
   # (e.g. man configuration.nix or on https://nixos.org/nixos/options.html).
-  system.stateVersion = "21.05"; # Did you read the comment?
+  system.stateVersion = import ../version.nix;
 
 }
 
diff --git a/home-manager/common.nix b/home-manager/common.nix
index de16c6b..1333545 100644
--- a/home-manager/common.nix
+++ b/home-manager/common.nix
@@ -14,7 +14,7 @@
   # You can update Home Manager without changing this value. See
   # the Home Manager release notes for a list of state version
   # changes in each release.
-  home.stateVersion = "21.05";
+  home.stateVersion = import ../version.nix;
 
   # Let Home Manager install and manage itself.
   programs.home-manager.enable = true;
diff --git a/version.nix b/version.nix
new file mode 100644
index 0000000..4fbd8a3
--- /dev/null
+++ b/version.nix
@@ -0,0 +1 @@
+"21.05"