diff --git a/node.gyp b/node.gyp
index 9de3492834..b4a3e461fa 100644
--- a/node.gyp
+++ b/node.gyp
@@ -125,6 +125,7 @@
       ],
 
       'defines': [
+        'NODE_WANT_INTERNALS=1',
         'ARCH="<(target_arch)"',
         'PLATFORM="<(OS)"',
       ],
diff --git a/src/node.h b/src/node.h
index 03ae934edf..e0df48e88f 100644
--- a/src/node.h
+++ b/src/node.h
@@ -67,20 +67,8 @@
 #include <node_isolate.h>
 #include <node_object_wrap.h>
 
-#ifndef offset_of
-// g++ in strict mode complains loudly about the system offsetof() macro
-// because it uses NULL as the base address.
-#define offset_of(type, member) \
-  ((intptr_t) ((char *) &(((type *) 8)->member) - 8))
-#endif
-
-#ifndef container_of
-#define container_of(ptr, type, member) \
-  ((type *) ((char *) (ptr) - offset_of(type, member)))
-#endif
-
-#ifndef ARRAY_SIZE
-#define ARRAY_SIZE(a) (sizeof((a)) / sizeof((a)[0]))
+#if NODE_WANT_INTERNALS
+# include "node_internals.h"
 #endif
 
 #ifndef NODE_STRINGIFY
diff --git a/src/node_internals.h b/src/node_internals.h
new file mode 100644
index 0000000000..8088e229ec
--- /dev/null
+++ b/src/node_internals.h
@@ -0,0 +1,99 @@
+// Copyright Joyent, Inc. and other Node contributors.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a
+// copy of this software and associated documentation files (the
+// "Software"), to deal in the Software without restriction, including
+// without limitation the rights to use, copy, modify, merge, publish,
+// distribute, sublicense, and/or sell copies of the Software, and to permit
+// persons to whom the Software is furnished to do so, subject to the
+// following conditions:
+//
+// The above copyright notice and this permission notice shall be included
+// in all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
+// NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
+// DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
+// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
+// USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+#ifndef SRC_NODE_INTERNALS_H_
+#define SRC_NODE_INTERNALS_H_
+
+namespace node {
+
+#ifndef offset_of
+// g++ in strict mode complains loudly about the system offsetof() macro
+// because it uses NULL as the base address.
+#define offset_of(type, member) \
+  ((intptr_t) ((char *) &(((type *) 8)->member) - 8))
+#endif
+
+#ifndef container_of
+#define container_of(ptr, type, member) \
+  ((type *) ((char *) (ptr) - offset_of(type, member)))
+#endif
+
+#ifndef ARRAY_SIZE
+#define ARRAY_SIZE(a) (sizeof((a)) / sizeof((a)[0]))
+#endif
+
+//
+// isolates support
+//
+#if HAVE_ISOLATES
+
+# if _WIN32
+#  define THREAD __declspec(thread)
+# else
+#  define THREAD __thread
+# endif
+
+# define TLS(type, name)      THREAD type* __tls_##name
+# define VAR(name)            (*__tls_##name)
+# define EMPTY(name)          (__tls_##name == NULL)
+# define ASSIGN(name, val)    ((__tls_##name) = P(val))
+
+# define LAZY_ASSIGN(name, val) \
+  do if (!__tls_##name) ((__tls_##name) = P(val)); while (0)
+
+template <class T> inline v8::Persistent<T>* P(v8::Handle<T> v)
+{
+  return new v8::Persistent<T>(v8::Persistent<T>::New(v));
+}
+
+inline v8::Persistent<v8::String>* P(const char* symbol)
+{
+  return new v8::Persistent<v8::String>(
+    v8::Persistent<v8::String>::New(
+      v8::String::NewSymbol(symbol)));
+}
+
+#else // !HAVE_ISOLATES
+
+# define THREAD             /* nothing */
+# define TLS(type, name)    type name
+# define VAR(name)          (name)
+# define EMPTY(name)        ((name).IsEmpty())
+# define ASSIGN(name, val)  ((name) = P(val))
+
+# define LAZY_ASSIGN(name, val) \
+  do if ((name).IsEmpty()) (name) = P(val); while (0)
+
+template <class T> inline v8::Persistent<T> P(v8::Handle<T> v)
+{
+  return v8::Persistent<T>(v);
+}
+
+inline v8::Persistent<v8::String> P(const char* symbol)
+{
+  return v8::Persistent<v8::String>::New(
+    v8::String::NewSymbol(symbol));
+}
+#endif // HAVE_ISOLATES
+
+} // namespace node
+
+#endif // SRC_NODE_INTERNALS_H_