diff --git a/nixos/modules/services/web-apps/plantuml-server.nix b/nixos/modules/services/web-apps/plantuml-server.nix
index 5ac3bc5226b2..f4bf43f56b98 100644
--- a/nixos/modules/services/web-apps/plantuml-server.nix
+++ b/nixos/modules/services/web-apps/plantuml-server.nix
@@ -58,8 +58,8 @@ in
 
       graphvizPackage = mkOption {
         type = types.package;
-        default = pkgs.graphviz_2_32;
-        defaultText = literalExpression "pkgs.graphviz_2_32";
+        default = pkgs.graphviz;
+        defaultText = literalExpression "pkgs.graphviz";
         description = "Package containing the dot executable.";
       };
 
diff --git a/pkgs/tools/misc/plantuml-server/default.nix b/pkgs/tools/misc/plantuml-server/default.nix
index eef6cdc11d5f..6afaf0fbb348 100644
--- a/pkgs/tools/misc/plantuml-server/default.nix
+++ b/pkgs/tools/misc/plantuml-server/default.nix
@@ -1,13 +1,13 @@
 { lib, stdenv, fetchFromGitHub, maven, jdk8_headless }:
 
 let
-  version = "1.2021.7";
+  version = "1.2021.12";
 
   src = fetchFromGitHub {
     owner = "plantuml";
     repo = "plantuml-server";
     rev = "v${version}";
-    sha256 = "sha256-kY7b3ocm1zudGIf72MNMZDUG2t2FFqucRr3kRaFv7mo=";
+    sha256 = "sha256:016mrs4djbaid1ma5922dvq372pphbzzmjzsjalj2dqp60538xll";
   };
 
   # perform fake build to make a fixed-output derivation out of the files downloaded from maven central
@@ -28,7 +28,7 @@ let
     installPhase = ''find $out/.m2 -type f -regex '.+\(\.lastUpdated\|resolver-status\.properties\|_remote\.repositories\)' -delete'';
     outputHashAlgo = "sha256";
     outputHashMode = "recursive";
-    outputHash = "sha256-HzT5rBycrd48KskWKAGtkMKdCDQ8NPYADVWZh8K0ll4=";
+    outputHash = "sha256:12w1iw9c5j7y9hhaip07j3aszjiiakkww1v3zszlj15fj8jgqyf2";
   };
 in