diff --git a/src/harfbuzz-buffer.c b/src/harfbuzz-buffer.c
index 8f9539a9d..4b25a5f12 100644
--- a/src/harfbuzz-buffer.c
+++ b/src/harfbuzz-buffer.c
@@ -356,5 +356,9 @@ _hb_buffer_replace_output_glyph( HB_Buffer buffer,
 HB_INTERNAL FT_UShort
 _hb_buffer_allocate_ligid( HB_Buffer buffer )
 {
-  return ++buffer->max_ligID;
+  buffer->max_ligID++;
+  if (HB_UNLIKELY (buffer->max_ligID == 0))
+    buffer->max_ligID++;
+
+  return buffer->max_ligID;
 }
diff --git a/src/harfbuzz-impl.h b/src/harfbuzz-impl.h
index 2215d2c40..dc89fa679 100644
--- a/src/harfbuzz-impl.h
+++ b/src/harfbuzz-impl.h
@@ -49,6 +49,9 @@ FT_BEGIN_HEADER
 # define FT_UNUSED(arg) ((arg) = (arg))
 #endif
 
+#define HB_LIKELY(cond) (cond)
+#define HB_UNLIKELY(cond) (cond)
+
 #include "ftglue.h"
 
 #define ARRAY_LEN(Array) ((int)(sizeof (Array) / sizeof (Array)[0]))