diff --git a/flake.nix b/flake.nix
index f1fab72..3ae0072 100644
--- a/flake.nix
+++ b/flake.nix
@@ -30,6 +30,13 @@
               python3
             ];
           };
+          packages.default = pkgs.stdenv.mkDerivation rec {
+            pname = "4-variable-simplifier";
+            version = "1.0";
+            src = ./.;
+            nativeBuildInputs = with pkgs; [ gcc gnumake ];
+            buildInputs = with pkgs; [ readline.dev ];
+          };
       });
 }
 
diff --git a/makefile b/makefile
index a4d67d3..c6c0741 100644
--- a/makefile
+++ b/makefile
@@ -1,6 +1,7 @@
 
 # vim: noexpandtab tabstop=4 :
 
+PREFIX ?= ${out}
 PREFIX ?= ${HOME}
 
 args =
@@ -14,21 +15,23 @@ cflags = -Werror -Wall -Wextra -Wstrict-prototypes -Wfatal-errors
 
 cflags += -O3
 
-cflags += -Wno-unused
+# cflags += -Wno-unused
 
 ldflags += -lreadline -lm
 
-/tmp/4-variable-simplifier: main.c
+bin/4-variable-simplifier: main.c | bin/
 	$(cc) $(cppflags) $(cflags) $< -o $@ $(ldflags)
 
-run: /tmp/4-variable-simplifier
+bin/:
+	mkdir -pv bin
+
+run: bin/4-variable-simplifier
 	$< $(args)
 
 install: ${PREFIX}/bin/4-variable-simplifier
 
-${PREFIX}/bin/4-variable-simplifier: /tmp/4-variable-simplifier
+${PREFIX}/bin/4-variable-simplifier: bin/4-variable-simplifier
 	mkdir -pv ${PREFIX}/bin/
 	cp -vau $< $@
 
-# nix --extra-experimental-features nix-command --extra-experimental-features flakes develop --command 'make'