Support dfont font files (#949)

diff --git a/src/main.cc b/src/main.cc
index ca0fcc5..873d240 100644
--- a/src/main.cc
+++ b/src/main.cc
@@ -78,6 +78,9 @@
   case OpenTypeFontFile::Typ1Tag:
     printf ("Obsolete Apple Type1 font in SFNT container\n");
     break;
+  case OpenTypeFontFile::DFontTag:
+    printf ("DFont Mac Resource Fork\n");
+    break;
   default:
     printf ("Unknown font format\n");
     break;