diff --git a/pkgs/tools/graphics/pikchr/default.nix b/pkgs/tools/graphics/pikchr/default.nix
index c8c1bd8d9515..aed3d485c4ad 100644
--- a/pkgs/tools/graphics/pikchr/default.nix
+++ b/pkgs/tools/graphics/pikchr/default.nix
@@ -1,16 +1,17 @@
 { lib
 , stdenv
-, fetchurl
+, fetchfossil
 }:
 
 stdenv.mkDerivation {
   pname = "pikchr";
   # To update, use the last check-in in https://pikchr.org/home/timeline?r=trunk
-  version = "unstable-2022-06-20";
+  version = "unstable-2022-12-07";
 
-  src = fetchurl {
-    url = "https://pikchr.org/home/tarball/d9ee756594b6eb64/pikchr.tar.gz";
-    sha256 = "sha256-ML+gymFrBay1kly7NYsxo0I1qNMoZPzNI3ClBTrWlHw=";
+  src = fetchfossil {
+    url = "https://pikchr.org/home";
+    rev = "21ca6b843d65c404";
+    sha256 = "sha256-fp06GqpLa/szRCS54KJ+SkT602oWvK3KyDFFjTmpNfI=";
   };
 
   # can't open generated html files