diff --git a/cmake/node_build.cmake b/cmake/node_build.cmake
index 295bb3e632..9d89432f00 100644
--- a/cmake/node_build.cmake
+++ b/cmake/node_build.cmake
@@ -62,6 +62,7 @@ set(node_sources
   src/node_script.cc
   src/node_os.cc
   src/node_dtrace.cc
+  src/node_string.cc
   src/node_natives.h
   ${node_extra_src})
 
diff --git a/src/node.cc b/src/node.cc
index b05e9aca9a..884c4a41c4 100644
--- a/src/node.cc
+++ b/src/node.cc
@@ -48,6 +48,7 @@
 #include <node_stdio.h>
 #include <node_javascript.h>
 #include <node_version.h>
+#include <node_string.h>
 #ifdef HAVE_OPENSSL
 # include <node_crypto.h>
 #endif
@@ -1269,7 +1270,7 @@ static void ReportException(TryCatch &try_catch, bool show_line) {
 }
 
 // Executes a str within the current v8 context.
-Local<Value> ExecuteString(Local<String> source, Local<Value> filename) {
+Local<Value> ExecuteString(Handle<String> source, Handle<Value> filename) {
   HandleScope scope;
   TryCatch try_catch;
 
@@ -2036,8 +2037,8 @@ static void Load(int argc, char *argv[]) {
 
   TryCatch try_catch;
 
-  Local<Value> f_value = ExecuteString(String::New(MainSource()),
-                                       String::New("node.js"));
+  Local<Value> f_value = ExecuteString(MainSource(),
+                                       IMMUTABLE_STRING("node.js"));
   if (try_catch.HasCaught())  {
     ReportException(try_catch, true);
     exit(10);
diff --git a/src/node_javascript.cc b/src/node_javascript.cc
index 95005eeb15..e0cc5b5c3e 100644
--- a/src/node_javascript.cc
+++ b/src/node_javascript.cc
@@ -1,6 +1,7 @@
 #include <v8.h>
 #include "node.h"
 #include "node_natives.h"
+#include "node_string.h"
 #include <string.h>
 #include <strings.h>
 
@@ -8,8 +9,8 @@ using namespace v8;
 
 namespace node {
 
-const char* MainSource() {
-  return node_native;
+Handle<String> MainSource() {
+  return BUILTIN_ASCII_ARRAY(node_native, sizeof(node_native)-1);
 }
 
 void DefineJavaScript(v8::Handle<v8::Object> target) {
@@ -18,14 +19,10 @@ void DefineJavaScript(v8::Handle<v8::Object> target) {
   for (int i = 0; natives[i].name; i++) {
     if (natives[i].source != node_native) {
       Local<String> name = String::New(natives[i].name);
-      // TODO: Use ExternalAsciiStringResource for source
-      // Might need to do some assertions in js2c about chars > 128
-      Local<String> source = String::New(natives[i].source);
+      Handle<String> source = BUILTIN_ASCII_ARRAY(natives[i].source, natives[i].source_len);
       target->Set(name, source);
     }
   }
 }
 
-
-
 }  // namespace node
diff --git a/src/node_javascript.h b/src/node_javascript.h
index 4df3bfa31e..9d682bd694 100644
--- a/src/node_javascript.h
+++ b/src/node_javascript.h
@@ -3,6 +3,6 @@
 namespace node {
 
 void DefineJavaScript(v8::Handle<v8::Object> target);
-const char* MainSource();
+v8::Handle<v8::String> MainSource();
 
 }  // namespace node
diff --git a/src/node_string.cc b/src/node_string.cc
new file mode 100644
index 0000000000..806d7afc90
--- /dev/null
+++ b/src/node_string.cc
@@ -0,0 +1,18 @@
+#include "node_string.h"
+
+namespace node {
+
+using namespace v8;
+
+Handle<String> ImmutableAsciiSource::CreateFromLiteral(
+    const char *string_literal,
+    size_t length) {
+  HandleScope scope;
+
+  Local<String> ret = String::NewExternal(new ImmutableAsciiSource(
+      string_literal,
+      length));
+  return scope.Close(ret);
+}
+
+}
diff --git a/src/node_string.h b/src/node_string.h
new file mode 100644
index 0000000000..1854cc2933
--- /dev/null
+++ b/src/node_string.h
@@ -0,0 +1,42 @@
+#ifndef SRC_NODE_STRING_H_
+#define SRC_NODE_STRING_H_
+
+#include <v8.h>
+
+namespace node {
+
+#define IMMUTABLE_STRING(string_literal)                                \
+  ::node::ImmutableAsciiSource::CreateFromLiteral(                      \
+      string_literal "", sizeof(string_literal) - 1)
+#define BUILTIN_ASCII_ARRAY(array, len)                                 \
+  ::node::ImmutableAsciiSource::CreateFromLiteral(array, len)
+
+class ImmutableAsciiSource : public v8::String::ExternalAsciiStringResource {
+ public:
+  static v8::Handle<v8::String> CreateFromLiteral(const char *string_literal,
+                                                  size_t length);
+
+  ImmutableAsciiSource(const char *src, size_t src_len)
+      : buffer_(src),
+        buf_len_(src_len) {
+  }
+
+  ~ImmutableAsciiSource() {
+  }
+
+  const char *data() const {
+      return buffer_;
+  }
+
+  size_t length() const {
+      return buf_len_;
+  }
+
+ private:
+  const char *buffer_;
+  size_t buf_len_;
+};
+
+}  // namespace node
+
+#endif  // SRC_NODE_STRING_H_
diff --git a/tools/js2c.py b/tools/js2c.py
index 8ef644ee19..fd8b25b1a4 100755
--- a/tools/js2c.py
+++ b/tools/js2c.py
@@ -53,7 +53,7 @@ def ToCArray(filename, lines):
 
     value = ord(chr)
 
-    if value > 128:
+    if value >= 128:
       print 'non-ascii value ' + filename + ':' + str(row) + ':' + str(col)
       sys.exit(1);
 
@@ -220,6 +220,7 @@ namespace node {
 struct _native {
   const char* name;
   const char* source;
+  size_t source_len;
 };
 
 static const struct _native natives[] = {
@@ -236,7 +237,7 @@ static const struct _native natives[] = {
 
 
 NATIVE_DECLARATION = """\
-  { "%(id)s", %(id)s_native },
+  { "%(id)s", %(id)s_native, sizeof(%(id)s_native)-1 },
 """
 
 SOURCE_DECLARATION = """\
diff --git a/wscript b/wscript
index 5f242b7225..dc23707ba8 100644
--- a/wscript
+++ b/wscript
@@ -801,6 +801,7 @@ def build(bld):
     src/node_script.cc
     src/node_os.cc
     src/node_dtrace.cc
+    src/node_string.cc
   """
 
   if sys.platform.startswith("win32"):