diff --git a/pkgs/tools/typesetting/tex/blahtexml/default.nix b/pkgs/tools/typesetting/tex/blahtexml/default.nix
index 43981eb2ae92..fb7605924023 100644
--- a/pkgs/tools/typesetting/tex/blahtexml/default.nix
+++ b/pkgs/tools/typesetting/tex/blahtexml/default.nix
@@ -14,6 +14,11 @@ stdenv.mkDerivation rec {
   postPatch = lib.optionalString stdenv.cc.isClang ''
     substituteInPlace makefile \
       --replace "\$(CXX)" "\$(CXX) -std=c++98"
+  '' +
+  # fix the doc build on TeX Live 2023
+  ''
+    substituteInPlace Documentation/manual.tex \
+      --replace '\usepackage[utf8x]{inputenc}' '\usepackage[utf8]{inputenc}'
   '';
 
   outputs = [ "out" "doc" ];