--- rtfreadr.c
+++ rtfreadr.c
@@ -107,13 +107,13 @@
                         {
                             if (ch < 'a' || ch > 'f')
                                 return ecInvalidHex;
-                            b += (char) ch - 'a';
+                            b += (char) ch - 'a'+10;
                         }
                         else
                         {
                             if (ch < 'A' || ch > 'F')
                                 return ecInvalidHex;
-                            b += (char) ch - 'A';
+                            b += (char) ch - 'A'+10;
                         }
                     }
                     cNibble--;