Index: fontbox/src/main/java/org/apache/fontbox/cff/CFFParser.java
===================================================================
--- fontbox/src/main/java/org/apache/fontbox/cff/CFFParser.java	(revision 1554746)
+++ fontbox/src/main/java/org/apache/fontbox/cff/CFFParser.java	(working copy)
@@ -584,7 +584,8 @@
         }
         else
         {
-            return CFFStandardString.getName(0);
+            // technically this maps to .notdef, but we need a unique glyph name
+            return "SID" + index;
         }
     }