diff --git a/src/hb-ucdn.cc b/src/hb-ucdn.cc
index a884e3ffd..d8404b294 100644
--- a/src/hb-ucdn.cc
+++ b/src/hb-ucdn.cc
@@ -160,6 +160,10 @@ static const hb_script_t ucdn_script_translate[] =
     HB_SCRIPT_NEWA,
     HB_SCRIPT_OSAGE,
     HB_SCRIPT_TANGUT,
+    HB_SCRIPT_MASARAM_GONDI,
+    HB_SCRIPT_NUSHU,
+    HB_SCRIPT_SOYOMBO,
+    HB_SCRIPT_ZANABAZAR_SQUARE,
 };
 
 static hb_unicode_combining_class_t
diff --git a/src/hb-ucdn/Makefile.sources b/src/hb-ucdn/Makefile.sources
index 52778d46c..cb823b605 100644
--- a/src/hb-ucdn/Makefile.sources
+++ b/src/hb-ucdn/Makefile.sources
@@ -3,5 +3,5 @@ NULL =
 LIBHB_UCDN_sources = \
 	ucdn.h \
 	ucdn.c \
-	unicodedata_db.h \
+	ucdn_db.h \
 	$(NULL)
diff --git a/src/hb-ucdn/ucdn.c b/src/hb-ucdn/ucdn.c
index f4e9be17c..30747fea2 100644
--- a/src/hb-ucdn/ucdn.c
+++ b/src/hb-ucdn/ucdn.c
@@ -23,7 +23,6 @@ typedef struct {
     unsigned char category;
     unsigned char combining;
     unsigned char bidi_class;
-    unsigned char mirrored;
     unsigned char east_asian_width;
     unsigned char script;
     unsigned char linebreak_class;
@@ -43,7 +42,7 @@ typedef struct {
     short count, index;
 } Reindex;
 
-#include "unicodedata_db.h"
+#include "ucdn_db.h"
 
 /* constants required for Hangul (de)composition */
 #define SBASE 0xAC00
@@ -91,20 +90,30 @@ static const unsigned short *get_decomp_record(uint32_t code)
     return &decomp_data[index];
 }
 
-static int get_comp_index(uint32_t code, const Reindex *idx)
+static int compare_reindex(const void *a, const void *b)
 {
-    int i;
-
-    for (i = 0; idx[i].start; i++) {
-        const Reindex *cur = &idx[i];
-        if (code < cur->start)
-            return -1;
-        if (code <= cur->start + cur->count) {
-            return cur->index + (code - cur->start);
-        }
-    }
+    Reindex *ra = (Reindex *)a;
+    Reindex *rb = (Reindex *)b;
 
-    return -1;
+    if (ra->start < rb->start)
+        return -1;
+    else if (ra->start > (rb->start + rb->count))
+        return 1;
+    else
+        return 0;
+}
+
+static int get_comp_index(uint32_t code, const Reindex *idx, size_t len)
+{
+    Reindex *res;
+    Reindex r = {0, 0, 0};
+    r.start = code;
+    res = (Reindex *) bsearch(&r, idx, len, sizeof(Reindex), compare_reindex);
+
+    if (res != NULL)
+        return res->index + (code - res->start);
+    else
+        return -1;
 }
 
 static int compare_mp(const void *a, const void *b)
@@ -127,8 +136,8 @@ static BracketPair *search_bp(uint32_t code)
     BracketPair *res;
 
     bp.from = code;
-    res = bsearch(&bp, bracket_pairs, BIDI_BRACKET_LEN, sizeof(BracketPair),
-            compare_bp);
+    res = (BracketPair *) bsearch(&bp, bracket_pairs, BIDI_BRACKET_LEN,
+                                 sizeof(BracketPair), compare_bp);
     return res;
 }
 
@@ -154,23 +163,18 @@ static int hangul_pair_decompose(uint32_t code, uint32_t *a, uint32_t *b)
 
 static int hangul_pair_compose(uint32_t *code, uint32_t a, uint32_t b)
 {
-    if (b < VBASE || b >= (TBASE + TCOUNT))
-        return 0;
-
-    if ((a < LBASE || a >= (LBASE + LCOUNT))
-            && (a < SBASE || a >= (SBASE + SCOUNT)))
-        return 0;
-
-    if (a >= SBASE) {
+    if (a >= SBASE && a < (SBASE + SCOUNT) && b >= TBASE && b < (TBASE + TCOUNT)) {
         /* LV,T */
         *code = a + (b - TBASE);
         return 3;
-    } else {
+    } else if (a >= LBASE && a < (LBASE + LCOUNT) && b >= VBASE && b < (VBASE + VCOUNT)) {
         /* L,V */
         int li = a - LBASE;
         int vi = b - VBASE;
         *code = SBASE + li * NCOUNT + vi * TCOUNT;
         return 2;
+    } else {
+        return 0;
     }
 }
 
@@ -178,7 +182,7 @@ static uint32_t decode_utf16(const unsigned short **code_ptr)
 {
     const unsigned short *code = *code_ptr;
 
-    if ((code[0] & 0xd800) != 0xd800) {
+    if (code[0] < 0xd800 || code[0] > 0xdc00) {
         *code_ptr += 1;
         return (uint32_t)code[0];
     } else {
@@ -215,7 +219,7 @@ int ucdn_get_bidi_class(uint32_t code)
 
 int ucdn_get_mirrored(uint32_t code)
 {
-    return get_ucd_record(code)->mirrored;
+    return ucdn_mirror(code) != code;
 }
 
 int ucdn_get_script(uint32_t code)
@@ -264,12 +268,9 @@ uint32_t ucdn_mirror(uint32_t code)
     MirrorPair mp = {0};
     MirrorPair *res;
 
-    if (get_ucd_record(code)->mirrored == 0)
-        return code;
-
     mp.from = code;
-    res = bsearch(&mp, mirror_pairs, BIDI_MIRROR_LEN, sizeof(MirrorPair),
-            compare_mp);
+    res = (MirrorPair *) bsearch(&mp, mirror_pairs, BIDI_MIRROR_LEN,
+                                sizeof(MirrorPair), compare_mp);
 
     if (res == NULL)
         return code;
@@ -326,8 +327,8 @@ int ucdn_compose(uint32_t *code, uint32_t a, uint32_t b)
     if (hangul_pair_compose(code, a, b))
         return 1;
 
-    l = get_comp_index(a, nfc_first);
-    r = get_comp_index(b, nfc_last);
+    l = get_comp_index(a, nfc_first, sizeof(nfc_first) / sizeof(Reindex));
+    r = get_comp_index(b, nfc_last, sizeof(nfc_last) / sizeof(Reindex));
 
     if (l < 0 || r < 0)
         return 0;
diff --git a/src/hb-ucdn/ucdn.h b/src/hb-ucdn/ucdn.h
index f694dc5a8..71a1e4b30 100644
--- a/src/hb-ucdn/ucdn.h
+++ b/src/hb-ucdn/ucdn.h
@@ -206,6 +206,10 @@ typedef unsigned __int64 uint64_t;
 #define UCDN_SCRIPT_NEWA 135
 #define UCDN_SCRIPT_OSAGE 136
 #define UCDN_SCRIPT_TANGUT 137
+#define UCDN_SCRIPT_MASARAM_GONDI 138
+#define UCDN_SCRIPT_NUSHU 139
+#define UCDN_SCRIPT_SOYOMBO 140
+#define UCDN_SCRIPT_ZANABAZAR_SQUARE 141
 
 #define UCDN_LINEBREAK_CLASS_OP 0
 #define UCDN_LINEBREAK_CLASS_CL 1
@@ -247,6 +251,9 @@ typedef unsigned __int64 uint64_t;
 #define UCDN_LINEBREAK_CLASS_SG 37
 #define UCDN_LINEBREAK_CLASS_SP 38
 #define UCDN_LINEBREAK_CLASS_XX 39
+#define UCDN_LINEBREAK_CLASS_ZWJ 40
+#define UCDN_LINEBREAK_CLASS_EB 41
+#define UCDN_LINEBREAK_CLASS_EM 42
 
 #define UCDN_GENERAL_CATEGORY_CC 0
 #define UCDN_GENERAL_CATEGORY_CF 1