diff --git a/nixos/machines/hera/cloud.nix b/nixos/machines/hera/cloud.nix
index a33b7652..b5ed01e5 100644
--- a/nixos/machines/hera/cloud.nix
+++ b/nixos/machines/hera/cloud.nix
@@ -81,7 +81,7 @@ let
 
         postgresql = {
           enable = true;
-          package = pkgs.postgresql_9_6;
+          package = pkgs.postgresql_12;
         };
       };
       systemd = {
@@ -137,7 +137,9 @@ let
   };
 in {
   systemd.services."container@cloud" = { inherit serviceConfig unitConfig; };
-  systemd.services."container@chor-cloud" = { inherit serviceConfig unitConfig; };
+  systemd.services."container@chor-cloud" = {
+    inherit serviceConfig unitConfig;
+  };
   services = {
     nginx = {
       enable = true;
diff --git a/nixos/roles/matrix-synapse.nix b/nixos/roles/matrix-synapse.nix
index 3bab7ce7..7514584b 100644
--- a/nixos/roles/matrix-synapse.nix
+++ b/nixos/roles/matrix-synapse.nix
@@ -35,7 +35,10 @@ in {
     };
 
     # Postgres
-    postgresql.enable = true;
+    postgresql = {
+      enable = true;
+      package = pkgs.postgresql_12;
+    };
 
     # Synapse
     matrix-synapse = let
diff --git a/nixos/roles/update-postgres.nix b/nixos/roles/update-postgres.nix
new file mode 100644
index 00000000..37b6a1a6
--- /dev/null
+++ b/nixos/roles/update-postgres.nix
@@ -0,0 +1,29 @@
+{ config, pkgs, ... }:
+{
+  containers.temp-pg.config.services.postgresql = {
+    enable = true;
+    package = pkgs.postgresql_12;
+  };
+  environment.systemPackages =
+    let newpg = config.containers.temp-pg.config.services.postgresql;
+    in [
+      (pkgs.writeScriptBin "upgrade-pg-cluster" ''
+        set -x
+        export OLDDATA="${config.services.postgresql.dataDir}"
+        export NEWDATA="${newpg.dataDir}"
+        export OLDBIN="${config.services.postgresql.package}/bin"
+        export NEWBIN="${newpg.package}/bin"
+
+        install -d -m 0700 -o postgres -g postgres "$NEWDATA"
+        cd "$NEWDATA"
+        sudo -u postgres $NEWBIN/initdb -D "$NEWDATA"
+
+        systemctl stop postgresql    # old one
+
+        sudo -u postgres $NEWBIN/pg_upgrade \
+          --old-datadir "$OLDDATA" --new-datadir "$NEWDATA" \
+          --old-bindir $OLDBIN --new-bindir $NEWBIN \
+          "$@"
+      '')
+    ];
+}