diff --git a/nixops/chiron-hardware-configuration.nix b/nixops/chiron-hardware-configuration.nix
index 719dac4..81fe8ef 100644
--- a/nixops/chiron-hardware-configuration.nix
+++ b/nixops/chiron-hardware-configuration.nix
@@ -27,4 +27,6 @@
 
   boot.loader.systemd-boot.enable = true;
   boot.loader.efi.canTouchEfiVariables = true;
+
+  system.stateVersion = "19.03";
 }
diff --git a/nixops/cnc-hardware-configuration.nix b/nixops/cnc-hardware-configuration.nix
index a5ae41a..8ab44a3 100644
--- a/nixops/cnc-hardware-configuration.nix
+++ b/nixops/cnc-hardware-configuration.nix
@@ -26,4 +26,6 @@
   boot.loader.grub.device = "/dev/sda";
 
   services.xserver.videoDrivers = ["intel"];
+
+  system.stateVersion = "19.03";
 }
diff --git a/nixops/desktop.nix b/nixops/desktop.nix
index 6acfdb0..2ea9d40 100644
--- a/nixops/desktop.nix
+++ b/nixops/desktop.nix
@@ -163,10 +163,4 @@ in
   nix.extraOptions = ''
     experimental-features = nix-command flakes
   '';
-
-  # This value determines the NixOS release with which your system is to be
-  # compatible, in order to avoid breaking some software such as database
-  # servers. You should change this only after NixOS release notes say you
-  # should.
-  system.stateVersion = "19.03"; # Did you read the comment?
 }
diff --git a/nixops/franz-hardware-configuration.nix b/nixops/franz-hardware-configuration.nix
index af19008..334b8af 100644
--- a/nixops/franz-hardware-configuration.nix
+++ b/nixops/franz-hardware-configuration.nix
@@ -31,4 +31,6 @@
 
   boot.loader.systemd-boot.enable = true;
   boot.loader.efi.canTouchEfiVariables = true;
+
+  system.stateVersion = "21.05";
 }
diff --git a/nixops/hera-hardware-configuration.nix b/nixops/hera-hardware-configuration.nix
index ab6c465..b4addfc 100644
--- a/nixops/hera-hardware-configuration.nix
+++ b/nixops/hera-hardware-configuration.nix
@@ -37,4 +37,6 @@
   networking.networkmanager.enable = false;
   networking.useDHCP = false;
   networking.interfaces.br0.useDHCP = true;
+
+  system.stateVersion = "19.03";
 }
diff --git a/nixops/hestia-hardware-configuration.nix b/nixops/hestia-hardware-configuration.nix
index 69d5e89..abdaba0 100644
--- a/nixops/hestia-hardware-configuration.nix
+++ b/nixops/hestia-hardware-configuration.nix
@@ -27,4 +27,6 @@
 
   boot.loader.systemd-boot.enable = true;
   boot.loader.efi.canTouchEfiVariables = true;
+
+  system.stateVersion = "19.03";
 }
diff --git a/nixops/juno-hardware-configuration.nix b/nixops/juno-hardware-configuration.nix
index bb8e0da..b933262 100644
--- a/nixops/juno-hardware-configuration.nix
+++ b/nixops/juno-hardware-configuration.nix
@@ -27,4 +27,6 @@
 
   boot.loader.systemd-boot.enable = true;
   boot.loader.efi.canTouchEfiVariables = true;
+
+  system.stateVersion = "19.03";
 }
diff --git a/nixops/light.nix b/nixops/light.nix
index 308d802..9b2dc0d 100644
--- a/nixops/light.nix
+++ b/nixops/light.nix
@@ -133,10 +133,4 @@ in
   nix.binaryCachePublicKeys = ["nixbld.m-labs.hk-1:5aSRVA5b320xbNvu30tqxVPXpld73bhtOeH6uAjRyHc="];
   nix.binaryCaches = ["https://nixbld.m-labs.hk" "https://cache.nixos.org"];
   nix.sandboxPaths = ["/opt"];
-
-  # This value determines the NixOS release with which your system is to be
-  # compatible, in order to avoid breaking some software such as database
-  # servers. You should change this only after NixOS release notes say you
-  # should.
-  system.stateVersion = "19.03"; # Did you read the comment?
 }
diff --git a/nixops/old-nixbld-hardware-configuration.nix b/nixops/old-nixbld-hardware-configuration.nix
index 1adc81b..2e936e0 100644
--- a/nixops/old-nixbld-hardware-configuration.nix
+++ b/nixops/old-nixbld-hardware-configuration.nix
@@ -35,4 +35,6 @@
 
   services.xserver.videoDrivers = [ "nvidia" ];
   services.xserver.displayManager.gdm.wayland = false;
+
+  system.stateVersion = "19.03";
 }
diff --git a/nixops/zeus-hardware-configuration.nix b/nixops/zeus-hardware-configuration.nix
index 27419aa..6a2b961 100644
--- a/nixops/zeus-hardware-configuration.nix
+++ b/nixops/zeus-hardware-configuration.nix
@@ -27,4 +27,6 @@
 
   boot.loader.systemd-boot.enable = true;
   boot.loader.efi.canTouchEfiVariables = true;
+
+  system.stateVersion = "19.03";
 }