diff --git a/.github/workflows/build.yaml b/.github/workflows/build.yaml
index cbb9e1c2..06da2b32 100644
--- a/.github/workflows/build.yaml
+++ b/.github/workflows/build.yaml
@@ -1,4 +1,4 @@
-name: Build
+name: Build PDFs
 
 on:
   - push
@@ -13,34 +13,44 @@ jobs:
     steps:
       - name: Set up Git repository
         uses: actions/checkout@v2
+        with:
+          fetch-depth: 1
 
       - name: Create global variables
         id: version
         run: echo "::set-output name=version::$(git rev-parse --short HEAD)"
 
+  determine-matrix:
+    name: Figure out the packages we need to build
+    runs-on: ubuntu-latest
+    needs: [dependencies]
+
+    outputs:
+      matrix: ${{ steps.set-matrix.outputs.matrix }}
+
+    steps:
+      - name: Set up Git repository
+        uses: actions/checkout@v2
+        with:
+          fetch-depth: 1
+
+      - name: Install the Nix package manager
+        uses: cachix/install-nix-action@v16
+
+      - id: set-matrix
+        run: |
+          echo "::set-output name=matrix::$(
+            nix eval --json --impure \
+              --expr 'builtins.attrNames (import ./.).packages.x86_64-linux'
+          )"
+
   build:
     name: Build documents
-    needs: dependencies
+    needs: determine-matrix
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        sources:
-          - input: ctfp
-            output:
-              reader: category-theory-for-programmers.pdf
-              print: category-theory-for-programmers-print.pdf
-          - input: ctfp-scala
-            output:
-              reader: category-theory-for-programmers-scala.pdf
-              print: category-theory-for-programmers-print-scala.pdf
-          - input: ctfp-reason
-            output:
-              reader: category-theory-for-programmers-reason.pdf
-              print: category-theory-for-programmers-print-reason.pdf
-          - input: ctfp-ocaml
-            output:
-              reader: category-theory-for-programmers-ocaml.pdf
-              print: category-theory-for-programmers-print-ocaml.pdf
+        packages: ${{fromJson(needs.determine-matrix.outputs.matrix)}}
 
     steps:
       - name: Set up Git repository
@@ -48,18 +58,16 @@ jobs:
         with:
           fetch-depth: 1
 
-      - name: Create necessary build file (version.tex)
-        run: |
-          echo -n -e "\\\newcommand{\OPTversion}{$(git rev-parse --short HEAD)}" > src/version.tex
       - name: Install Nix
         uses: cachix/install-nix-action@v16
 
-      - name: Build ${{ matrix.sources.input }}
+      - name: Build ${{ matrix.packages }}.pdf
         run: |
-          nix build .#${{ matrix.sources.input }}
+          nix build .#${{ matrix.packages }}
           mkdir -p out
           cp -ar ./result/* out/
-      - name: Upload build assets (${{ matrix.sources.output.print }})
+
+      - name: Upload build assets (${{ matrix.packages }}.pdf)
         uses: actions/upload-artifact@v2
         with:
           name: ctfp
@@ -86,39 +94,24 @@ jobs:
   assets:
     name: Upload release assets
     runs-on: ubuntu-latest
-    needs: [dependencies, release]
+    needs: [determine-matrix, dependencies, release]
     strategy:
       matrix:
-        assets:
-          - source: category-theory-for-programmers-print.pdf
-            destination: category-theory-for-programmers--print
-          - source: category-theory-for-programmers.pdf
-            destination: category-theory-for-programmers
-          - source: category-theory-for-programmers-print-scala.pdf
-            destination: category-theory-for-programmers--print--scala
-          - source: category-theory-for-programmers-scala.pdf
-            destination: category-theory-for-programmers--reader--scala
-          - source: category-theory-for-programmers-print-ocaml.pdf
-            destination: category-theory-for-programmers--print--ocaml
-          - source: category-theory-for-programmers-ocaml.pdf
-            destination: category-theory-for-programmers--reader--ocaml
-          - source: category-theory-for-programmers-print-reason.pdf
-            destination: category-theory-for-programmers--print--reason
-          - source: category-theory-for-programmers-reason.pdf
-            destination: category-theory-for-programmers--reader--reason
+        packages: ${{fromJson(needs.determine-matrix.outputs.matrix)}}
+
     steps:
-      - name: Download build assets (${{ matrix.assets.source }})
+      - name: Download build assets (${{ matrix.packages }}.pdf)
         uses: actions/download-artifact@v2
         with:
           name: ctfp
           path: ctfp
 
-      - name: Upload release assets (${{ matrix.assets.destination }}--${{ needs.dependencies.outputs.version }}.pdf)
+      - name: Upload release assets (${{ matrix.packages }}--${{ needs.dependencies.outputs.version }}.pdf)
         uses: actions/upload-release-asset@v1
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
         with:
           upload_url: ${{ needs.release.outputs.upload_url }}
-          asset_path: ctfp/${{ matrix.assets.source }}
-          asset_name: ${{ matrix.assets.destination }}--${{ needs.dependencies.outputs.version }}.pdf
+          asset_path: ctfp/${{ matrix.packages }}.pdf
+          asset_name: ${{ matrix.packages }}--${{ needs.dependencies.outputs.version }}.pdf
           asset_content_type: application/pdf
diff --git a/flake.nix b/flake.nix
index 86a25f30..d983e7cf 100644
--- a/flake.nix
+++ b/flake.nix
@@ -5,9 +5,10 @@
   inputs.utils.url = "github:numtide/flake-utils";
 
   outputs = { self, nixpkgs, utils }: utils.lib.eachDefaultSystem (system: let
-    pkgs = nixpkgs.legacyPackages.${system};
     inherit (nixpkgs) lib;
 
+    pkgs = nixpkgs.legacyPackages.${system};
+
     ###########################################################################
     # LaTeX Environment
     texliveEnv = pkgs.texlive.combine {
@@ -86,57 +87,63 @@
       propagatedBuildInputs = with pythonPkgs; [ pygments ];
     };
 
-    pythonEnv = python.withPackages (
-      pyPkgs: with pyPkgs; [
-        pygments
-        pygments-style-github
-      ]
-    );
+    pythonEnv = python.withPackages (p: [ p.pygments pygments-style-github ]);
 
-    mkPackageName = edition:
-      "ctfp${lib.optionalString (edition != null) "-${edition}"}";
+    commonAttrs = {
+      nativeBuildInputs = [ texliveEnv pythonEnv pkgs.which ];
+      FONTCONFIG_FILE = pkgs.makeFontsConf {
+        fontDirectories = with pkgs; [ inconsolata-lgc libertine libertinus ];
+      };
+    };
 
-    mkPackage = isShell: edition: pkgs.stdenv.mkDerivation {
-      name = mkPackageName edition;
-      src = if isShell then null else self;
+    mkLatex = variant: edition: let
+      maybeVariant = lib.optionalString (variant != null) "-${variant}";
+      maybeEdition = lib.optionalString (edition != null) "-${edition}";
+      variantStr = if variant == null then "reader" else variant;
+      suffix = maybeVariant + maybeEdition;
+      basename = "ctfp-${variantStr}${maybeEdition}";
+      version = self.shortRev or self.lastModifiedDate;
+    in pkgs.stdenv.mkDerivation (commonAttrs // {
+      inherit basename version;
 
-      makeFlags = [
-        "-C" "src" "OUTPUT_DIR=$(out)"
-        "GIT_VER=${self.rev or self.lastModifiedDate}"
-      ];
+      name = "ctfp${suffix}-${version}";
+      fullname = "ctfp${suffix}";
+      src = "${self}/src";
 
-      buildFlags = lib.optional (edition != null) edition;
+      configurePhase = ''
+        echo -n "\\newcommand{\\OPTversion}{$version}" > version.tex
+      '';
 
-      dontInstall = true;
+      buildPhase = ''
+        latexmk -shell-escape -interaction=nonstopmode -halt-on-error \
+          -norc -jobname=ctfp -pdflatex="xelatex %O %S" -pdf "$basename.tex"
+      '';
 
-      FONTCONFIG_FILE = pkgs.makeFontsConf {
-        fontDirectories = with pkgs; [ inconsolata-lgc libertine libertinus ];
-      };
+      installPhase = "install -m 0644 -vD ctfp.pdf \"$out/$fullname.pdf\"";
 
-      buildInputs = with pkgs; [
-        # Misc. build tooling.
-        gnumake
-        git
-        python3Packages.virtualenv
-        which
-        # LaTeX Environment (with all associated libraries and packages).
-        texliveEnv
-        # Python Environment (with all associated libraries and packages).
-        pythonEnv
-      ];
-    };
+      passthru.packageName = "ctfp${suffix}";
+    });
 
     editions = [ null "scala" "ocaml" "reason" ];
-
+    variants = [ null "print" ];
   in {
-    # Nix build
-    packages = lib.listToAttrs (map (edition: {
-      name = mkPackageName edition;
-      value = mkPackage false edition;
-    }) editions);
-
+    # nix build .#ctfp
+    # nix build .#ctfp-print
+    # nix build .#ctfp-print-ocaml
+    # etc etc
+    packages = lib.listToAttrs (lib.concatMap (variant: map (edition: rec {
+      name = value.packageName;
+      value = mkLatex variant edition;
+    }) editions) variants);
+
+    # nix build .
     defaultPackage = self.packages.${system}.ctfp;
 
-    devShell = mkPackage true null;
+    # nix develop .
+    devShell = pkgs.mkShell (commonAttrs // {
+      nativeBuildInputs = commonAttrs.nativeBuildInputs ++ [
+        pkgs.git pkgs.gnumake
+      ];
+    });
   });
 }