diff --git a/src/hb-common.h b/src/hb-common.h
index d404353ce..1cdbd5eaf 100644
--- a/src/hb-common.h
+++ b/src/hb-common.h
@@ -30,11 +30,11 @@
 #include <stdint.h>
 
 # ifdef __cplusplus
-#  define HB_BEGIN_DECLS() extern "C" { extern int hb_dummy_prototype (int)
-#  define HB_END_DECLS() } extern "C" int hb_dummy_prototype (int)
+#  define HB_BEGIN_DECLS() extern "C" { extern int _hb_dummy_prototype1 (int)
+#  define HB_END_DECLS() } extern "C" int _hb_dummy_prototype2 (int)
 # else /* !__cplusplus */
-#  define HB_BEGIN_DECLS()   extern int hb_dummy_prototype (int)
-#  define HB_END_DECLS()     extern int hb_dummy_prototype (int)
+#  define HB_BEGIN_DECLS()   extern int _hb_dummy_prototype1 (int)
+#  define HB_END_DECLS()     extern int _hb_dummy_prototype2 (int)
 # endif /* !__cplusplus */
 
 typedef int hb_bool_t;
@@ -47,8 +47,7 @@ typedef uint32_t hb_tag_t;
 				((const char *) s)[3]))
 
 typedef uint32_t hb_codepoint_t;
-
-/* XXX */
-typedef struct HB_BufferRec_ hb_buffer_t;
+typedef int32_t hb_position_t;
+typedef int32_t hb_16dot16_t;
 
 #endif /* HB_COMMON_H */
diff --git a/src/hb-private.h b/src/hb-private.h
index 3dca04907..aeb91359c 100644
--- a/src/hb-private.h
+++ b/src/hb-private.h
@@ -27,6 +27,8 @@
 #ifndef HB_PRIVATE_H
 #define HB_PRIVATE_H
 
+#include <hb-common.h>
+
 #include <glib.h>
 
 /* Macros to convert to/from BigEndian */
@@ -39,12 +41,36 @@
 #define hb_be_uint64_t	GUINT64_TO_BE
 #define hb_be_int64_t	GINT64_TO_BE
 
-#define HB_LIKELY	G_LIKEYLY
+#define HB_LIKELY	G_LIKELY
 #define HB_UNLIKELY	G_UNLIKELY
 #define HB_UNUSED(arg) ((arg) = (arg))
+#define HB_GNUC_UNUSED	G_GNUC_UNUSED
 
 
-#include <assert.h>
+#include <stdlib.h>
+#include <stdio.h> /* XXX */
+
+/* Basics */
+
+#undef MIN
+#define MIN(a,b) ((a) < (b) ? (a) : (b))
+
+#ifndef HB_INTERNAL
+# define HB_INTERNAL
+#endif
+
+#ifndef NULL
+# define NULL ((void *)0)
+#endif
+
+#ifndef FALSE
+# define FALSE 0
+#endif
+
+#ifndef TRUE
+# define TRUE 1
+#endif
+
 
 #define _ASSERT_STATIC1(_line, _cond) typedef int _static_assert_on_line_##_line##_failed[(_cond)?1:-1]
 #define _ASSERT_STATIC0(_line, _cond) _ASSERT_STATIC1 (_line, (_cond))
@@ -52,11 +78,55 @@
 
 #define ASSERT_SIZE(_type, _size) ASSERT_STATIC (sizeof (_type) == (_size))
 
+
+/* Return the number of 1 bits in mask.
+ *
+ * GCC 3.4 supports a "population count" builtin, which on many targets is
+ * implemented with a single instruction. There is a fallback definition
+ * in libgcc in case a target does not have one, which should be just as
+ * good as the open-coded solution below, (which is "HACKMEM 169").
+ */
+static inline unsigned int
+_hb_popcount32 (uint32_t mask)
+{
+#if __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4)
+    return __builtin_popcount (mask);
+#else
+    register int y;
+
+    y = (mask >> 1) &033333333333;
+    y = mask - y - ((y >>1) & 033333333333);
+    return (((y + (y >> 3)) & 030707070707) % 077);
+#endif
+}
+
 /*
  * buffer
  */
 
 /* XXX */
 #define HB_BUFFER_GLYPH_PROPERTIES_UNKNOWN 0xFFFF
+#define HB_OT_GPOS_NO_LAST ((unsigned int) -1)
+
+/* XXX */
+typedef enum {
+  /* no error */
+  HB_Err_Ok                           = 0x0000,
+  HB_Err_Not_Covered                  = 0xFFFF,
+
+  /* _hb_err() is called whenever returning the following errors,
+   * and in a couple places for HB_Err_Not_Covered too. */
+
+  /* programmer error */
+  HB_Err_Invalid_Argument             = 0x1A66,
+
+  /* font error */
+  HB_Err_Invalid_SubTable_Format      = 0x157F,
+  HB_Err_Invalid_SubTable             = 0x1570,
+  HB_Err_Read_Error                   = 0x6EAD,
+
+  /* system error */
+  HB_Err_Out_Of_Memory                = 0xDEAD
+} HB_Error;
 
 #endif /* HB_PRIVATE_H */