diff --git a/first-interpreter/.gitignore b/first-interpreter/.gitignore
index e35d885..a863071 100644
--- a/first-interpreter/.gitignore
+++ b/first-interpreter/.gitignore
@@ -1 +1,2 @@
 _build
+interpreter
diff --git a/first-interpreter/Makefile b/first-interpreter/Makefile
new file mode 100644
index 0000000..2ea1f7b
--- /dev/null
+++ b/first-interpreter/Makefile
@@ -0,0 +1,36 @@
+ifndef VERBOSE
+.SILENT:
+endif
+
+CC = gcc
+CFLAGS = -Wall -Wextra -ggdb
+
+.DEFAULT_TARGET = interpreter
+
+interpreter: src/main.c build/run.o
+	$(CC) $(CFLAGS) $< -o $@ build/run.o build/ast.o build/lex.o build/parse.o build/execute.o
+
+build/ast.o: src/ast.c src/ast.h
+	mkdir -p build/
+	$(CC) $(CFLAGS) -c $< -o $@
+
+build/lex.o: src/lex.c src/lex.h
+	mkdir -p build/
+	$(CC) $(CFLAGS) -c $< -o $@
+
+build/parse.o: src/parse.c src/parse.h build/ast.o build/lex.o
+	$(CC) $(CFLAGS) -c $< -o $@
+
+build/execute.o: src/execute.c src/execute.h build/ast.o
+	$(CC) $(CFLAGS) -c $< -o $@
+
+build/run.o: src/run.c src/run.h build/ast.o build/lex.o build/parse.o build/execute.o
+	$(CC) $(CFLAGS) -c $< -o $@
+
+.PHONY clean run:
+clean:
+	rm -rf build
+	rm -rf interpreter
+
+run: interpreter
+	./interpreter program.code
diff --git a/first-interpreter/build.hs b/first-interpreter/build.hs
deleted file mode 100755
index d24ec78..0000000
--- a/first-interpreter/build.hs
+++ /dev/null
@@ -1,46 +0,0 @@
-#!/usr/bin/env cabal
-{- cabal:
-build-depends:
-  base,
-  bytestring,
-  cereal,
-  hspec,
-  process,
-  shake,
--}
--- initial version taken from https://shakebuild.com/manual
-import Development.Shake
-import Development.Shake.FilePath
-import Development.Shake.Util
-
-cc = "gcc"
-flags = "-ggdb"
-clearCcCache = removeFilesAfter "build" ["//*"]
-
-main :: IO ()
-main = shakeArgs shakeOptions{shakeFiles="_build"} $ do
-  want ["_build/interpreter" <.> exe]
-
-  phony "clean" $ do
-    putInfo "Cleaning files in _build"
-    removeFilesAfter "_build" ["//*"]
-    clearCcCache
-    removeFilesAfter "newdist" ["//*"]
-    cmd_ "cabal" "clean"
-
-  phony "run" $ do
-    need ["_build/interpreter" <.> exe]
-    putInfo "Running interpreter"
-    cmd_ "_build/interpreter" ["program.code"]
-
-  "_build/interpreter" <.> exe %> \out -> do
-    cs <- getDirectoryFiles "src" ["//*.c"]
-    let os = ["_build" </> "normal" </> "src" </> c -<.> "o" | c <- cs]
-    need os
-    cmd_ (cc <> " " <> flags <> " -o") [out] os
-
-  "_build/normal//*.o" %> \out -> do
-    let c = dropDirectory1 $ dropDirectory1 $ out -<.> "c"
-    let m = out -<.> "m"
-    cmd_ (cc <> " " <> flags <> " -c") [c] "-o" [out] "-MMD -MF" [m]
-    neededMakefileDependencies m
diff --git a/first-interpreter/src/execute.c b/first-interpreter/src/execute.c
index 0e18459..8886234 100644
--- a/first-interpreter/src/execute.c
+++ b/first-interpreter/src/execute.c
@@ -86,9 +86,9 @@ int* lookup(char* name, Memory memory, Environment env) {
 
 int eval_expr(Expr expr, Memory memory, Environment env) {
     switch (expr.tag) {
+    default:
     case LITERAL: {
         return expr.data.integer;
-        break;
     }
     case VARIABLE: {
         int* result = lookup(expr.data.variable, memory, env);
@@ -98,7 +98,6 @@ int eval_expr(Expr expr, Memory memory, Environment env) {
         } else {
             return *result;
         }
-        break;
     }
     case FUNCTION: {
         if (strcmp(expr.data.function.name, "print") == 0) {
@@ -131,7 +130,6 @@ int eval_expr(Expr expr, Memory memory, Environment env) {
             }
         }
         return 0;
-        break;
     }
     }
 }
diff --git a/first-interpreter/src/main.c b/first-interpreter/src/main.c
index 55ec140..930cfd0 100644
--- a/first-interpreter/src/main.c
+++ b/first-interpreter/src/main.c
@@ -1,6 +1,6 @@
 #include <stdlib.h>
 #include <stdio.h>
-#include "interpreter.h"
+#include "run.h"
 
 int main(int argc, char** argv) {
     // Read file
diff --git a/first-interpreter/src/interpreter.c b/first-interpreter/src/run.c
similarity index 100%
rename from first-interpreter/src/interpreter.c
rename to first-interpreter/src/run.c
diff --git a/first-interpreter/src/interpreter.h b/first-interpreter/src/run.h
similarity index 100%
rename from first-interpreter/src/interpreter.h
rename to first-interpreter/src/run.h