diff --git a/.gitignore b/.gitignore
index 64d859d..e570fbe 100644
--- a/.gitignore
+++ b/.gitignore
@@ -318,5 +318,9 @@ TSWLatexianTemp*
 # End of https://www.toptal.com/developers/gitignore/api/direnv,latex
 
 
-# LuaTex
+### lualatex ###
 luatex.*/
+
+### Nix ###
+result
+result/
\ No newline at end of file
diff --git a/flake.lock b/flake.lock
index 302ca36..3bf0746 100644
--- a/flake.lock
+++ b/flake.lock
@@ -20,16 +20,16 @@
     },
     "nixpkgs": {
       "locked": {
-        "lastModified": 1757034884,
-        "narHash": "sha256-PgLSZDBEWUHpfTRfFyklmiiLBE1i1aGCtz4eRA3POao=",
-        "owner": "nixos",
+        "lastModified": 1757020766,
+        "narHash": "sha256-PLoSjHRa2bUbi1x9HoXgTx2AiuzNXs54c8omhadyvp0=",
+        "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "ca77296380960cd497a765102eeb1356eb80fed0",
+        "rev": "fe83bbdde2ccdc2cb9573aa846abe8363f79a97a",
         "type": "github"
       },
       "original": {
-        "owner": "nixos",
-        "ref": "nixpkgs-unstable",
+        "owner": "NixOS",
+        "ref": "nixos-25.05",
         "repo": "nixpkgs",
         "type": "github"
       }
diff --git a/flake.nix b/flake.nix
index 9379dbc..04de325 100644
--- a/flake.nix
+++ b/flake.nix
@@ -1,18 +1,60 @@
 {
+  description = "LaTeX Beamer Presentation for GPUL Schools: Software Libre";
   inputs = {
-    nixpkgs.url = "github:nixos/nixpkgs/nixpkgs-unstable";
-    flake-utils.url = "github:numtide/flake-utils";
+    nixpkgs.url = github:NixOS/nixpkgs/nixos-25.05;
+    flake-utils.url = github:numtide/flake-utils;
   };
 
-  outputs = { self, nixpkgs, flake-utils }:
-    flake-utils.lib.eachDefaultSystem (system:
-      let pkgs = nixpkgs.legacyPackages.${system}; in
-      {
+  outputs = {
+    self,
+    nixpkgs,
+    flake-utils,
+  }:
+    flake-utils.lib.eachDefaultSystem (
+      system: let
+        pkgs = nixpkgs.legacyPackages.${system};
+        tex = pkgs.texlive.combine {
+          inherit
+            (pkgs.texlive)
+            scheme-basic
+            latex-bin
+            latexmk
+            collection-langspanish
+            beamer
+            biblatex
+            biber
+            csquotes
+            emoji
+            fontspec
+            noto-emoji
+            ;
+        };
+        # tex = pkgs.texliveFull;
+      in rec {
+        packages = {
+          document = pkgs.stdenvNoCC.mkDerivation rec {
+            name = "latex-beamer-gpul-schools-software-libre";
+            src = self;
+            buildInputs = [pkgs.coreutils tex];
+            phases = ["unpackPhase" "buildPhase" "installPhase"];
+            buildPhase = ''
+              export PATH="${pkgs.lib.makeBinPath buildInputs}";
+              env TEXMFVAR=$(mktemp -d) \
+                SOURCE_DATE_EPOCH=${toString self.lastModified} \
+                latexmk -interaction=nonstopmode -pdf -lualatex \
+                -pretex="\pdfvariable suppressoptionalinfo 512\relax" \
+                -usepretex main.tex
+            '';
+            installPhase = ''
+              mkdir -p $out
+              cp main.pdf $out/
+            '';
+          };
+        };
+        defaultPackage = packages.document;
+
         devShells.default = pkgs.mkShell {
-          buildInputs = with pkgs; [
-            texstudio
-            texlive.combined.scheme-full
-          ];
+          buildInputs = packages.document.buildInputs;
         };
       }
     );
diff --git a/main.pdf b/main.pdf
deleted file mode 100644
index 30d2e84..0000000
Binary files a/main.pdf and /dev/null differ
diff --git a/main.tex b/main.tex
index 703b1f3..1d2b1a3 100644
--- a/main.tex
+++ b/main.tex
@@ -2,7 +2,7 @@
 \usepackage[spanish]{babel}
 \usetheme{Madrid}
 
-\usepackage[backend=biber]{biblatex}
+\usepackage[backend=biber, language=auto]{biblatex}
 \usepackage{csquotes}
 \addbibresource{references.bib}
 
@@ -17,7 +17,7 @@
 
 \institute[GPUL]{Grupo de Programadores e Usuarios de Linux}
 
-\date{GPUL Schools 25/26}
+\date{\today}
 
 \logo{\includegraphics[height=1cm]{logo-gpul.png}}
 
@@ -117,10 +117,10 @@
 	\begin{frame}
 		\frametitle{Que facer despois desta charla?}
 		\begin{itemize}
-			\item<1-> Comprar manzanas
-			\item<2-> Ver Telecinco
-			\item<3-> Por el culo te la hinco
-			\item<4-> Jeje
+			\item<1-> A
+			\item<2-> B
+			\item<3-> C
+			\item<4-> D
 		\end{itemize}
 	\end{frame}
 	
diff --git a/references.bib b/references.bib
index 2d612a9..6c9aee1 100644
--- a/references.bib
+++ b/references.bib
@@ -1,4 +1,4 @@
-@@online{gnu_free_sw,
+@online{gnu_free_sw,
 	author       = {GNU \& FSF},
 	title        = {The Free Software Definition},
 	url          = {https://www.gnu.org/philosophy/free-sw.en.html},