diff --git a/src/hb-buffer.cc b/src/hb-buffer.cc
index db4edce..eddd5d0 100644
--- a/src/hb-buffer.cc
+++ b/src/hb-buffer.cc
@@ -37,8 +37,6 @@
 #define HB_DEBUG_BUFFER (HB_DEBUG+0)
 #endif
 
-#define _HB_BUFFER_UNICODE_FUNCS_DEFAULT (const_cast<hb_unicode_funcs_t *> (&_hb_unicode_funcs_default))
-
 /* Here is how the buffer works internally:
  *
  * There are two info pointers: info and out_info.  They always have
@@ -144,7 +142,7 @@
     return;
 
   hb_unicode_funcs_destroy (unicode);
-  unicode = _HB_BUFFER_UNICODE_FUNCS_DEFAULT;
+  unicode = hb_unicode_funcs_get_default ();
 
   hb_segment_properties_t default_props = _HB_BUFFER_PROPS_DEFAULT;
   props = default_props;
@@ -552,7 +550,7 @@
   static const hb_buffer_t _hb_buffer_nil = {
     HB_OBJECT_HEADER_STATIC,
 
-    _HB_BUFFER_UNICODE_FUNCS_DEFAULT,
+    const_cast<hb_unicode_funcs_t *> (&_hb_unicode_funcs_nil),
     _HB_BUFFER_PROPS_DEFAULT,
 
     true, /* in_error */
@@ -608,7 +606,8 @@
     return;
 
   if (!unicode)
-    unicode = _HB_BUFFER_UNICODE_FUNCS_DEFAULT;
+    unicode = hb_unicode_funcs_get_default ();
+
 
   hb_unicode_funcs_reference (unicode);
   hb_unicode_funcs_destroy (buffer->unicode);
diff --git a/src/hb-glib.cc b/src/hb-glib.cc
index 7af92cc..0462758 100644
--- a/src/hb-glib.cc
+++ b/src/hb-glib.cc
@@ -250,9 +250,6 @@
   /* We don't ifdef-out the fallback code such that compiler always
    * sees it and makes sure it's compilable. */
 
-  if (!a || !b)
-    return false;
-
   gchar utf8[12];
   gchar *normalized;
   int len;
@@ -367,22 +364,21 @@
   return utf8_decomposed_len;
 }
 
-extern HB_INTERNAL const hb_unicode_funcs_t _hb_glib_unicode_funcs;
-const hb_unicode_funcs_t _hb_glib_unicode_funcs = {
-  HB_OBJECT_HEADER_STATIC,
-
-  NULL, /* parent */
-  true, /* immutable */
-  {
-#define HB_UNICODE_FUNC_IMPLEMENT(name) hb_glib_unicode_##name,
-    HB_UNICODE_FUNCS_IMPLEMENT_CALLBACKS
-#undef HB_UNICODE_FUNC_IMPLEMENT
-  }
-};
-
 hb_unicode_funcs_t *
 hb_glib_get_unicode_funcs (void)
 {
+  static const hb_unicode_funcs_t _hb_glib_unicode_funcs = {
+    HB_OBJECT_HEADER_STATIC,
+
+    NULL, /* parent */
+    true, /* immutable */
+    {
+#define HB_UNICODE_FUNC_IMPLEMENT(name) hb_glib_unicode_##name,
+      HB_UNICODE_FUNCS_IMPLEMENT_CALLBACKS
+#undef HB_UNICODE_FUNC_IMPLEMENT
+    }
+  };
+
   return const_cast<hb_unicode_funcs_t *> (&_hb_glib_unicode_funcs);
 }
 
diff --git a/src/hb-icu.cc b/src/hb-icu.cc
index 5e92058..4bb7af2 100644
--- a/src/hb-icu.cc
+++ b/src/hb-icu.cc
@@ -33,7 +33,7 @@
 
 #include "hb-unicode-private.hh"
 
-#include <unicode/uversion.h>
+#include <unicode/uvernum.h>
 #include <unicode/uchar.h>
 #include <unicode/unorm.h>
 #include <unicode/ustring.h>
@@ -164,6 +164,10 @@
   return hb_icu_script_to_script (scriptCode);
 }
 
+#if U_ICU_VERSION_MAJOR_NUM >= 49
+static const UNormalizer2 *normalizer;
+#endif
+
 static hb_bool_t
 hb_icu_unicode_compose (hb_unicode_funcs_t *ufuncs HB_UNUSED,
 			hb_codepoint_t      a,
@@ -171,8 +175,17 @@
 			hb_codepoint_t     *ab,
 			void               *user_data HB_UNUSED)
 {
-  if (!a || !b)
-    return false;
+#if U_ICU_VERSION_MAJOR_NUM >= 49
+  {
+    UChar32 ret = unorm2_composePair (normalizer, a, b);
+    if (ret < 0) return false;
+    *ab = ret;
+    return true;
+  }
+#endif
+
+  /* We don't ifdef-out the fallback code such that compiler always
+   * sees it and makes sure it's compilable. */
 
   UChar utf16[4], normalized[5];
   unsigned int len;
@@ -207,6 +220,32 @@
 			  hb_codepoint_t     *b,
 			  void               *user_data HB_UNUSED)
 {
+#if U_ICU_VERSION_MAJOR_NUM >= 49
+  {
+    UChar decomposed[4];
+    int len;
+    UErrorCode icu_err = U_ZERO_ERROR;
+    len = unorm2_getRawDecomposition (normalizer, ab, decomposed,
+				      ARRAY_LENGTH (decomposed), &icu_err);
+    if (U_FAILURE (icu_err) || len < 0) return false;
+
+    len = u_countChar32 (decomposed, len);
+    if (len == 1) {
+      U16_GET_UNSAFE (decomposed, 0, *a);
+      *b = 0;
+      return *a != ab;
+    } else if (len == 2) {
+      len =0;
+      U16_NEXT_UNSAFE (decomposed, len, *a);
+      U16_NEXT_UNSAFE (decomposed, len, *b);
+    }
+    return true;
+  }
+#endif
+
+  /* We don't ifdef-out the fallback code such that compiler always
+   * sees it and makes sure it's compilable. */
+
   UChar utf16[2], normalized[2 * HB_UNICODE_MAX_DECOMPOSITION_LEN + 1];
   unsigned int len;
   hb_bool_t ret, err;
@@ -306,22 +345,28 @@
 }
 
 
-extern HB_INTERNAL const hb_unicode_funcs_t _hb_icu_unicode_funcs;
-const hb_unicode_funcs_t _hb_icu_unicode_funcs = {
-  HB_OBJECT_HEADER_STATIC,
-
-  NULL, /* parent */
-  true, /* immutable */
-  {
-#define HB_UNICODE_FUNC_IMPLEMENT(name) hb_icu_unicode_##name,
-    HB_UNICODE_FUNCS_IMPLEMENT_CALLBACKS
-#undef HB_UNICODE_FUNC_IMPLEMENT
-  }
-};
-
 hb_unicode_funcs_t *
 hb_icu_get_unicode_funcs (void)
 {
+  static const hb_unicode_funcs_t _hb_icu_unicode_funcs = {
+    HB_OBJECT_HEADER_STATIC,
+
+    NULL, /* parent */
+    true, /* immutable */
+    {
+#define HB_UNICODE_FUNC_IMPLEMENT(name) hb_icu_unicode_##name,
+      HB_UNICODE_FUNCS_IMPLEMENT_CALLBACKS
+#undef HB_UNICODE_FUNC_IMPLEMENT
+    }
+  };
+
+#if U_ICU_VERSION_MAJOR_NUM >= 49
+  if (!hb_atomic_ptr_get (&normalizer)) {
+    UErrorCode icu_err = U_ZERO_ERROR;
+    /* We ignore failure in getNFCInstace(). */
+    hb_atomic_ptr_cmpexch (&normalizer, NULL, unorm2_getNFCInstance (&icu_err));
+  }
+#endif
   return const_cast<hb_unicode_funcs_t *> (&_hb_icu_unicode_funcs);
 }
 
diff --git a/src/hb-unicode-private.hh b/src/hb-unicode-private.hh
index 53214b9..7ef5820 100644
--- a/src/hb-unicode-private.hh
+++ b/src/hb-unicode-private.hh
@@ -80,13 +80,14 @@
 			    hb_codepoint_t *ab)
   {
     *ab = 0;
+    if (unlikely (!a || !b)) return false;
     return func.compose (this, a, b, ab, user_data.compose);
   }
 
   inline hb_bool_t decompose (hb_codepoint_t ab,
 			      hb_codepoint_t *a, hb_codepoint_t *b)
   {
-    *a = *b = 0;
+    *a = ab; *b = 0;
     return func.decompose (this, ab, a, b, user_data.decompose);
   }
 
@@ -182,17 +183,7 @@
 };
 
 
-#ifdef HAVE_GLIB
-extern HB_INTERNAL const hb_unicode_funcs_t _hb_glib_unicode_funcs;
-#define _hb_unicode_funcs_default _hb_glib_unicode_funcs
-#elif defined(HAVE_ICU)
-extern HB_INTERNAL const hb_unicode_funcs_t _hb_icu_unicode_funcs;
-#define _hb_unicode_funcs_default _hb_icu_unicode_funcs
-#else
-#define HB_UNICODE_FUNCS_NIL 1
 extern HB_INTERNAL const hb_unicode_funcs_t _hb_unicode_funcs_nil;
-#define _hb_unicode_funcs_default _hb_unicode_funcs_nil
-#endif
 
 
 /* Modified combining marks */
diff --git a/src/hb-unicode.cc b/src/hb-unicode.cc
index 8979eaa..2e2d077 100644
--- a/src/hb-unicode.cc
+++ b/src/hb-unicode.cc
@@ -109,12 +109,44 @@
 }
 
 
+#define HB_UNICODE_FUNCS_IMPLEMENT_SET \
+  HB_UNICODE_FUNCS_IMPLEMENT (glib) \
+  HB_UNICODE_FUNCS_IMPLEMENT (icu) \
+  HB_UNICODE_FUNCS_IMPLEMENT (nil) \
+  /* ^--- Add new callbacks before nil */
+
+#define hb_nil_get_unicode_funcs hb_unicode_funcs_get_empty
+
+/* Prototype them all */
+#define HB_UNICODE_FUNCS_IMPLEMENT(set) \
+extern "C" hb_unicode_funcs_t *hb_##set##_get_unicode_funcs (void);
+HB_UNICODE_FUNCS_IMPLEMENT_SET
+#undef HB_UNICODE_FUNCS_IMPLEMENT
+
+
 hb_unicode_funcs_t *
 hb_unicode_funcs_get_default (void)
 {
-  return const_cast<hb_unicode_funcs_t *> (&_hb_unicode_funcs_default);
+#define HB_UNICODE_FUNCS_IMPLEMENT(set) \
+  return hb_##set##_get_unicode_funcs ();
+
+#ifdef HAVE_GLIB
+  HB_UNICODE_FUNCS_IMPLEMENT(glib)
+#elif defined(HAVE_ICU)
+  HB_UNICODE_FUNCS_IMPLEMENT(icu)
+#else
+#define HB_UNICODE_FUNCS_NIL 1
+  HB_UNICODE_FUNCS_IMPLEMENT(nil)
+#endif
+
+#undef HB_UNICODE_FUNCS_IMPLEMENT
 }
 
+#if !defined(HB_NO_UNICODE_FUNCS) && defined(HB_UNICODE_FUNCS_NIL)
+#pragma message("Could not find any Unicode functions implementation, you have to provide your own.")
+#pragma message("To suppress this warnings, define HB_NO_UNICODE_FUNCS.")
+#endif
+
 hb_unicode_funcs_t *
 hb_unicode_funcs_create (hb_unicode_funcs_t *parent)
 {
@@ -140,7 +172,6 @@
 }
 
 
-extern HB_INTERNAL const hb_unicode_funcs_t _hb_unicode_funcs_nil;
 const hb_unicode_funcs_t _hb_unicode_funcs_nil = {
   HB_OBJECT_HEADER_STATIC,
 
diff --git a/src/hb-warning.cc b/src/hb-warning.cc
index 8ff4d20..01adcea 100644
--- a/src/hb-warning.cc
+++ b/src/hb-warning.cc
@@ -37,11 +37,3 @@
 #if defined(HB_ATOMIC_INT_NIL) || defined(HB_MUTEX_IMPL_NIL)
 #pragma message("To suppress these warnings, define HB_NO_MT.")
 #endif
-
-
-#include "hb-unicode-private.hh"
-
-#if !defined(HB_NO_UNICODE_FUNCS) && defined(HB_UNICODE_FUNCS_NIL)
-#pragma message("Could not find any Unicode functions implementation, you have to provide your own.")
-#pragma message("To suppress this warnings, define HB_NO_UNICODE_FUNCS.")
-#endif