[merge] Use CmapSubtable.isUnicode()
diff --git a/Lib/fontTools/merge.py b/Lib/fontTools/merge.py
index 5f5bc2a..3e5acec 100644
--- a/Lib/fontTools/merge.py
+++ b/Lib/fontTools/merge.py
@@ -338,7 +338,7 @@
 def merge(self, m, tables):
 	# TODO Handle format=14.
 	cmapTables = [t for table in tables for t in table.tables
-		      if t.platformID == 3 and t.platEncID in [1, 10]]
+		      if t.isUnicode()]
 	# TODO Better handle format-4 and format-12 coexisting in same font.
 	# TODO Insert both a format-4 and format-12 if needed.
 	module = ttLib.getTableModule('cmap')