diff --git a/build.sh b/build.sh
new file mode 100644
index 0000000..53189bd
--- /dev/null
+++ b/build.sh
@@ -0,0 +1,62 @@
+#!/usr/bin/env bash
+
+# Following variables are set via sed in the buildPhase step
+PREFIX=""
+# Intentionally overriding PATH so supressing shellcheck
+# shellcheck disable=SC2123
+PATH=""
+NERDFONTS=""
+
+DEBUG=false
+DIR=$(mktemp -d)
+RES=$(pwd)/alejandro_resume.pdf
+LOG=$(pwd)/alejandro_resume.log
+
+function usage {
+echo "Usage: $(basename "$0") [-h] [-d] [-e EMAIL] [-p PHONENUMBER]"
+echo '    -h              Prints this usage message.'
+echo ""
+echo '    -d              Saves latexmk log file (will be named alejandro_resume.log)'
+echo ""
+echo '    -e EMAIL        Sets email address used when building document.'
+echo '                    Can also be set with EMAIL environment variable.'
+echo ""
+echo '    -p PHONENUMBER  Sets phone number used when building the document.'
+echo '                    Can also be set with PHONENUMBER environment variable.'
+}
+
+while getopts ':de:p:h' flag; do
+case $flag in
+  'd') DEBUG=true;;
+  # Overrides EMAIL and PHONENUMBER envvars if set
+  'e') EMAIL="$OPTARG";;
+  'p') PHONENUMBER="$OPTARG";;
+  'h') usage && exit;;
+  ?) usage && exit 1;;
+esac
+done
+
+cd "$PREFIX"/share || exit 1
+mkdir -p "$DIR/.texcache/texmf-var"
+
+export EMAIL
+export PHONENUMBER
+
+# Set via sed in buildPhase (needs to be set after we have input values (e.g.
+# EMAIL and PHONENUMBER)
+TEXVARS=""
+
+env TEXFMHOME="$DIR/.texcache" TEXMFVAR="$DIR/.texcache/texmf-var" \
+  OSFONTDIR="$NERDFONTS"/share/fonts \
+latexmk -interaction=nonstopmode -pdf -lualatex \
+-output-directory="$DIR" \
+-pretex="$TEXVARS" \
+-usepretex alejandro_resume.tex
+
+mv "$DIR/alejandro_resume.pdf" "$RES"
+
+if $DEBUG; then
+mv "$DIR/alejandro_resume.log" "$LOG"
+fi
+
+rm -rf "$DIR"
diff --git a/flake.nix b/flake.nix
index ced72ff..d7b1e3f 100644
--- a/flake.nix
+++ b/flake.nix
@@ -25,7 +25,7 @@
     # Create definitions like \def\email{$EMAIL}
     # Each \email command in the tex document will be populated by an EMAIL
     # variable (can be set as an environment variable)
-    texvars = toString (lib.concatMapStrings (x: ''\def\${x}{${"$" + lib.toUpper x}}'') vars);
+    texvars = toString (lib.concatMapStrings (x: ''\\def\\${x}{${"$" + lib.toUpper x}}'') vars);
   in {
     packages.${system} = {
       # inherit system;
@@ -34,60 +34,12 @@
         src = self;
         propogatedBuildInputs = [pkgs.coreutils nerdfonts-hack tex];
         phases = ["unpackPhase" "buildPhase" "installPhase"];
-        SCRIPT = ''
-          #!/usr/bin/env bash
-
-          prefix=${builtins.placeholder "out"}
-          export PATH="${lib.makeBinPath propogatedBuildInputs}";
-          DEBUG=false
-          DIR=$(mktemp -d)
-          RES=$(pwd)/alejandro_resume.pdf
-          LOG=$(pwd)/alejandro_resume.log
-
-          function usage {
-            echo "Usage: $(basename $0) [-h] [-d] [-e EMAIL] [-p PHONENUMBER]"
-            echo '    -h              Prints this usage message.'
-            echo ""
-            echo '    -d              Saves latexmk log file (will be named alejandro_resume.log)'
-            echo ""
-            echo '    -e EMAIL        Sets email address used when building document.'
-            echo '                    Can also be set with EMAIL environment variable.'
-            echo ""
-            echo '    -p PHONENUMBER  Sets phone number used when building the document.'
-            echo '                    Can also be set with PHONENUMBER environment variable.'
-          }
-
-          while getopts ':de:p:h' flag; do
-            case $flag in
-              'd') DEBUG=true;;
-              # Overrides EMAIL and PHONENUMBER envvars if set
-              'e') EMAIL="$OPTARG";;
-              'p') PHONENUMBER="$OPTARG";;
-              'h') usage && exit;;
-              ?) usage && exit 1;;
-            esac
-          done
-
-          cd $prefix/share
-          mkdir -p "$DIR/.texcache/texmf-var"
-
-          env TEXFMHOME="$DIR/.texcache" TEXMFVAR="$DIR/.texcache/texmf-var" \
-              OSFONTDIR=${nerdfonts-hack}/share/fonts \
-            latexmk -interaction=nonstopmode -pdf -lualatex \
-            -output-directory="$DIR" \
-            -pretex="${texvars}"\
-            -usepretex alejandro_resume.tex
-
-          mv "$DIR/alejandro_resume.pdf" "$RES"
-
-          if $DEBUG; then
-            mv "$DIR/alejandro_resume.log" "$LOG"
-          fi
-
-          rm -rf $DIR
-        '';
         buildPhase = ''
-          printenv SCRIPT > alejandro-resume
+          cp build.sh alejandro-resume
+          sed -i 's!PREFIX=""!PREFIX="${builtins.placeholder "out"}"!g' alejandro-resume
+          sed -i 's!PATH=""!PATH="${lib.makeBinPath propogatedBuildInputs}"!g' alejandro-resume
+          sed -i 's!TEXVARS=""!TEXVARS="${texvars}"!g' alejandro-resume
+          sed -i 's!NERDFONTS=""!NERDFONTS="${nerdfonts-hack}"!g' alejandro-resume
         '';
         installPhase = ''
           mkdir -p $out/{bin,share}
@@ -109,6 +61,7 @@
           pre-commit
           tex #TODO: Is this necessary?
           zathura # PDF Viewer
+          shellcheck
         ];
 
         shellHook = ''