diff --git a/.gitignore b/.gitignore
index 49c129e0..fa18aa19 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,6 +1,10 @@
-# Output directory.
+# Intermediate files directory.
 build/
 
+# Built applications.
+wren
+wrend
+
 # XCode user-specific stuff.
 xcuserdata/
 *.xccheckout
diff --git a/Makefile b/Makefile
index 79615b54..118f2f65 100644
--- a/Makefile
+++ b/Makefile
@@ -1,18 +1,53 @@
+# Compiler flags.
+CFLAGS = -std=c99 -Wall -Werror
+# TODO: Add -Wextra.
+DEBUG_CFLAGS = -O0 -DDEBUG
+RELEASE_CFLAGS = -Os
+
+# Files.
+SOURCES = $(wildcard src/*.c)
+HEADERS = $(wildcard src/*.h)
+OBJECTS = $(SOURCES:.c=.o)
+
+DEBUG_OBJECTS = $(addprefix build/debug/, $(notdir $(OBJECTS)))
+RELEASE_OBJECTS = $(addprefix build/release/, $(notdir $(OBJECTS)))
+
 .PHONY: all clean test docs corelib
 
-all:
-	gcc -Iinclude src/*.c -owren
-	mkdir -p build/Release
-	mv wren build/Release
+all: release
+
+# Debug build.
+debug: prep wrend
+
+wrend: $(DEBUG_OBJECTS)
+	$(CC) $(CFLAGS) $(DEBUG_CFLAGS) -Iinclude -o wrend $^
+
+build/debug/%.o: src/%.c include/wren.h $(HEADERS)
+	$(CC) -c $(CFLAGS) $(DEBUG_CFLAGS) -Iinclude -o $@ $<
+
+# Release build.
+release: prep wren
+
+wren: $(RELEASE_OBJECTS)
+	$(CC) $(CFLAGS) $(RELEASE_CFLAGS) -Iinclude -o wren $^
+
+build/release/%.o: src/%.c include/wren.h $(HEADERS)
+	$(CC) -c $(CFLAGS) $(RELEASE_CFLAGS) -Iinclude -o $@ $<
 
 clean:
-	rm -rf build
+	rm -rf build wren wrend
 
-test:
-	@./runtests
+prep:
+	mkdir -p build/debug build/release
 
+# Run the tests against the debug build of Wren.
+test: wrend
+	@./script/test.py
+
+# Generate the Wren site.
 docs:
-	@./make_docs
+	@./script/generate_docs.py --watch
 
+# Take the contents of corelib.wren and copy them into src/wren_core.c.
 corelib:
-	@./make_corelib
+	@./script/generate_corelib.py
diff --git a/benchmark/fannkuch.lua b/benchmark/fannkuch.lua
new file mode 100644
index 00000000..072b9c05
--- /dev/null
+++ b/benchmark/fannkuch.lua
@@ -0,0 +1,48 @@
+-- The Computer Language Benchmarks Game
+-- http://benchmarksgame.alioth.debian.org/
+-- contributed by Mike Pall
+
+local function fannkuch(n)
+  local p, q, s, sign, maxflips, sum = {}, {}, {}, 1, 0, 0
+  for i=1,n do p[i] = i; q[i] = i; s[i] = i end
+  repeat
+    -- Copy and flip.
+    local q1 = p[1]       -- Cache 1st element.
+    if q1 ~= 1 then
+      for i=2,n do q[i] = p[i] end    -- Work on a copy.
+      local flips = 1
+      repeat
+  local qq = q[q1]
+  if qq == 1 then       -- ... until 1st element is 1.
+    sum = sum + sign*flips
+    if flips > maxflips then maxflips = flips end -- New maximum?
+    break
+  end
+  q[q1] = q1
+  if q1 >= 4 then
+    local i, j = 2, q1 - 1
+    repeat q[i], q[j] = q[j], q[i]; i = i + 1; j = j - 1; until i >= j
+  end
+  q1 = qq; flips = flips + 1
+      until false
+    end
+    -- Permute.
+    if sign == 1 then
+      p[2], p[1] = p[1], p[2]; sign = -1  -- Rotate 1<-2.
+    else
+      p[2], p[3] = p[3], p[2]; sign = 1   -- Rotate 1<-2 and 1<-2<-3.
+      for i=3,n do
+  local sx = s[i]
+  if sx ~= 1 then s[i] = sx-1; break end
+  if i == n then return sum, maxflips end -- Out of permutations.
+  s[i] = i
+  -- Rotate 1<-...<-i+1.
+  local t = p[1]; for j=1,i do p[j] = p[j+1] end; p[i+1] = t
+      end
+    end
+  until false
+end
+
+local n = 9
+local sum, flips = fannkuch(n)
+io.write(sum, "\nPfannkuchen(", n, ") = ", flips, "\n")
\ No newline at end of file
diff --git a/benchmark/fannkuch.py b/benchmark/fannkuch.py
new file mode 100644
index 00000000..53e41106
--- /dev/null
+++ b/benchmark/fannkuch.py
@@ -0,0 +1,56 @@
+# The Computer Language Benchmarks Game
+# http://benchmarksgame.alioth.debian.org/
+
+#    contributed by Isaac Gouy
+#    converted to Java by Oleg Mazurov
+#    converted to Python by Buck Golemon
+#    modified by Justin Peel
+
+def fannkuch(n):
+    maxFlipsCount = 0
+    permSign = True
+    checksum = 0
+
+    perm1 = list(range(n))
+    count = perm1[:]
+    rxrange = range(2, n - 1)
+    nm = n - 1
+    while 1:
+        k = perm1[0]
+        if k:
+            perm = perm1[:]
+            flipsCount = 1
+            kk = perm[k]
+            while kk:
+                perm[:k+1] = perm[k::-1]
+                flipsCount += 1
+                k = kk
+                kk = perm[kk]
+            if maxFlipsCount < flipsCount:
+                maxFlipsCount = flipsCount
+            checksum += flipsCount if permSign else -flipsCount
+
+        # Use incremental change to generate another permutation
+        if permSign:
+            perm1[0],perm1[1] = perm1[1],perm1[0]
+            permSign = False
+        else:
+            perm1[1],perm1[2] = perm1[2],perm1[1]
+            permSign = True
+            for r in rxrange:
+                if count[r]:
+                    break
+                count[r] = r
+                perm0 = perm1[0]
+                perm1[:r+1] = perm1[1:r+2]
+                perm1[r+1] = perm0
+            else:
+                r = nm
+                if not count[r]:
+                    print( checksum )
+                    return maxFlipsCount
+            count[r] -= 1
+
+n = 9
+
+print(( "Pfannkuchen(%i) = %i" % (n, fannkuch(n)) ))
\ No newline at end of file
diff --git a/benchmark/fannkuch.rb b/benchmark/fannkuch.rb
new file mode 100644
index 00000000..14aeed10
--- /dev/null
+++ b/benchmark/fannkuch.rb
@@ -0,0 +1,60 @@
+def fannkuch(n)
+  p = (0..n).to_a
+  s = p.dup
+  q = p.dup
+  sign = 1
+  sum = maxflips = 0
+  while(true)
+    # flip.
+
+    if (q1 = p[1]) != 1
+      q[0..-1] = p
+      flips = 1
+      until (qq = q[q1]) == 1
+        q[q1] = q1
+        if q1 >= 4
+          i, j = 2, q1 - 1
+          while i < j
+            q[i], q[j] = q[j], q[i]
+            i += 1
+            j -= 1
+          end
+        end
+        q1 = qq
+        flips += 1
+      end
+      sum += sign * flips
+      maxflips = flips if flips > maxflips # New maximum?
+
+    end
+    # Permute.
+
+    if sign == 1
+      # Rotate 1<-2.
+
+      p[1], p[2] = p[2], p[1]
+      sign = -1
+    else
+      # Rotate 1<-2 and 1<-2<-3.
+
+      p[2], p[3] = p[3], p[2]
+      sign = 1
+      i = 3
+      while i <= n && s[i] == 1
+        return [sum, maxflips] if i == n     # Out of permutations.
+
+        s[i] = i
+        # Rotate 1<-...<-i+1.
+
+        t = p.delete_at(1)
+        i += 1
+        p.insert(i, t)
+      end
+      s[i] -= 1  if i <= n
+    end
+  end
+end
+
+n = 9
+sum, flips = fannkuch(n)
+printf "%d\nPfannkuchen(%d) = %d\n", sum, n, flips
\ No newline at end of file
diff --git a/benchmark/run_bench b/benchmark/run_bench
index 73fe2f06..bcd38a3d 100755
--- a/benchmark/run_bench
+++ b/benchmark/run_bench
@@ -3,10 +3,15 @@
 import argparse
 import math
 import os
+import os.path
 import re
 import subprocess
 import sys
 
+# Runs the tests.
+WREN_DIR = os.path.dirname(os.path.dirname(os.path.realpath(__file__)))
+BENCHMARK_DIR = os.path.join(WREN_DIR, 'benchmark')
+
 # How many times to run a given benchmark.
 NUM_TRIALS = 10
 
@@ -36,9 +41,8 @@ BENCHMARK("method_call", r"""true
 false""")
 
 LANGUAGES = [
-  ("wren",           ["../build/Release/wren"], ".wren"),
+  ("wren",           ["../wren"], ".wren"),
   ("lua",            ["lua"],                   ".lua"),
-#  ("luajit",          ["luajit"],                ".lua"),
   ("luajit (-joff)", ["luajit", "-joff"],       ".lua"),
   ("python",         ["python"],                ".py"),
   ("ruby",           ["ruby"],                  ".rb")
@@ -75,7 +79,7 @@ def run_trial(benchmark, language):
   """Runs one benchmark one time for one language."""
   args = []
   args.extend(language[1])
-  args.append(benchmark[0] + language[2])
+  args.append(os.path.join(BENCHMARK_DIR, benchmark[0] + language[2]))
   out = subprocess.check_output(args, universal_newlines=True)
   match = benchmark[1].match(out)
   if match:
@@ -91,7 +95,8 @@ def run_benchmark_language(benchmark, language):
   name = "{0} - {1}".format(benchmark[0], language[0])
   print "{0:30s}".format(name),
 
-  if not os.path.exists(benchmark[0] + language[2]):
+  if not os.path.exists(os.path.join(
+      BENCHMARK_DIR, benchmark[0] + language[2])):
     print "No implementation for this language"
     return
 
diff --git a/example/sokoban.wren b/example/sokoban.wren
new file mode 100644
index 00000000..0bb440c3
--- /dev/null
+++ b/example/sokoban.wren
@@ -0,0 +1 @@
+IO.print("Hello, world!")
diff --git a/make_corelib b/script/generate_corelib.py
similarity index 100%
rename from make_corelib
rename to script/generate_corelib.py
diff --git a/make_docs b/script/generate_docs.py
similarity index 100%
rename from make_docs
rename to script/generate_docs.py
diff --git a/runtests b/script/test.py
similarity index 89%
rename from runtests
rename to script/test.py
index d5310e62..83574cc2 100755
--- a/runtests
+++ b/script/test.py
@@ -8,29 +8,9 @@ from subprocess import Popen, PIPE
 import sys
 
 # Runs the tests.
-WREN_DIR = dirname(realpath(__file__))
+WREN_DIR = dirname(dirname(realpath(__file__)))
 TEST_DIR = join(WREN_DIR, 'test')
-
-if sys.platform == 'win32':
-  WREN_APP = join(WREN_DIR, 'Debug', 'wren.exe')
-  if not isfile(WREN_DIR):
-    WREN_APP = join(WREN_DIR, 'Release', 'wren.exe')
-  if not isfile(WREN_APP):
-    sys.exit('Cannot find wren.exe!')
-elif sys.platform.startswith('linux'):
-  WREN_APP = join(WREN_DIR, '1', 'out', 'Debug', 'wren')
-  if not isfile(WREN_APP):
-    WREN_APP = join(WREN_DIR, '1', 'out', 'Release', 'wren')
-  if not isfile(WREN_APP):
-    sys.exit('Cannot find wren!')
-elif sys.platform.startswith('darwin'):
-  WREN_APP = join(WREN_DIR, 'build', 'Debug', 'wren')
-  if not isfile(WREN_APP):
-    WREN_APP = join(WREN_DIR, 'build', 'Release', 'wren')
-  if not isfile(WREN_APP):
-    sys.exit('Cannot find wren!')
-else:
-  sys.exit('System not supported!')
+WREN_APP = join(WREN_DIR, 'wrend')
 
 EXPECT_PATTERN = re.compile(r'// expect: (.*)')
 EXPECT_ERROR_PATTERN = re.compile(r'// expect error')
diff --git a/src/main.c b/src/main.c
index 478b55e3..5d10ce16 100644
--- a/src/main.c
+++ b/src/main.c
@@ -9,9 +9,6 @@
 // This is the source file for the standalone command line interpreter. It is
 // not needed if you are embedding Wren in an application.
 
-// TODO: Don't hardcode this.
-#define MAX_LINE 1024
-
 static void failIf(bool condition, int exitCode, const char* format, ...)
 {
   if (!condition) return;
@@ -66,8 +63,10 @@ static int runRepl(WrenVM* vm)
   for (;;)
   {
     printf("> ");
-    char line[MAX_LINE];
-    fgets(line, MAX_LINE, stdin);
+
+    char* line = NULL;
+    size_t size = 0;
+    getline(&line, &size, stdin);
 
     // If stdin was closed (usually meaning the used entered Ctrl-D), exit.
     if (feof(stdin))
@@ -77,7 +76,10 @@ static int runRepl(WrenVM* vm)
     }
 
     // TODO: Handle failure.
-    wrenInterpret(vm, "(repl)", line);
+    wrenInterpret(vm, "Prompt", line);
+
+    free(line);
+
     // TODO: Figure out how this should work with wren API.
     /*
     ObjFn* fn = compile(vm, line);
diff --git a/src/wren_vm.c b/src/wren_vm.c
index 1d9c5f67..3a11c23f 100644
--- a/src/wren_vm.c
+++ b/src/wren_vm.c
@@ -478,7 +478,8 @@ static bool runInterpreter(WrenVM* vm)
     &&code_CLASS,
     &&code_SUBCLASS,
     &&code_METHOD_INSTANCE,
-    &&code_METHOD_STATIC
+    &&code_METHOD_STATIC,
+    &&code_END
   };
 
   #define INTERPRET_LOOP    DISPATCH();
@@ -1022,7 +1023,8 @@ static bool runInterpreter(WrenVM* vm)
     CASE_CODE(END):
       // A CODE_END should always be preceded by a CODE_RETURN. If we get here,
       // the compiler generated wrong code.
-      ASSERT(0, "Should not execute past end of bytecode.");
+      UNREACHABLE();
+      DISPATCH();
   }
 
   ASSERT(0, "Should not reach end of interpret.");