diff --git a/README.md b/README.md
index ec493ab..5941011 100644
--- a/README.md
+++ b/README.md
@@ -20,4 +20,15 @@ For details see,
      91–102). Springer.
 
 
+Installation
+------------
+
+    git clone git@github.com:dcjones/hat-trie.git
+    cd hat-trie
+    autoreconf -i
+    ./configure
+    make install
+
+To use the library, include `hat-trie.h` and link using `lhat-trie`.
+
 
diff --git a/src/common.h b/src/common.h
new file mode 100644
index 0000000..91dac33
--- /dev/null
+++ b/src/common.h
@@ -0,0 +1,19 @@
+/*
+ * This file is part of hat-trie.
+ *
+ * Copyright (c) 2011 by Daniel C. Jones <dcjones@cs.washington.edu>
+ *
+ *
+ * Common typedefs, etc.
+ *
+ */
+
+
+#ifndef HATTRIE_COMMON_H
+#define HATTRIE_COMMON_H
+
+typedef unsigned long value_t;
+
+#endif
+
+