diff --git a/stb_truetype.h b/stb_truetype.h
index c65d3d6..ad4d0d9 100644
--- a/stb_truetype.h
+++ b/stb_truetype.h
@@ -25,6 +25,7 @@
 //   Misc other:
 //       Ryan Gordon
 //       Simon Glass
+//       github:IntellectualKitty
 //
 //   Bug/warning reports/fixes:
 //       "Zer" on mollyrocket (with fix)
@@ -49,11 +50,10 @@
 //       Higor Euripedes
 //       Thomas Fields
 //       Derek Vinyard
-//       github:IntellectualKitty
 //
 // VERSION HISTORY
 //
-//   1.13 (2017-01-02) support OpenType fonts, certain Apple fonts,
+//   1.13 (2017-01-02) support OpenType fonts, certain Apple fonts, num-fonts-in-TTC function
 //   1.12 (2016-10-25) suppress warnings about casting away const with -Wcast-qual
 //   1.11 (2016-04-02) fix unused-variable warning
 //   1.10 (2016-04-02) user-defined fabs(); rare memory leak; remove duplicate typedef
@@ -98,7 +98,8 @@
 //
 //   "Load" a font file from a memory buffer (you have to keep the buffer loaded)
 //           stbtt_InitFont()
-//           stbtt_GetFontOffsetForIndex()        -- use for TTC font collections
+//           stbtt_GetFontOffsetForIndex()        -- indexing for TTC font collections
+//           stbtt_GetNumberOfFonts()             -- number of fonts for TTC font collections
 //
 //   Render a unicode codepoint to a bitmap
 //           stbtt_GetCodepointBitmap()           -- allocates and returns a bitmap
@@ -632,14 +633,19 @@ struct stbtt_pack_context {
 //
 //
 
+STBTT_DEF int stbtt_GetNumberOfFonts(const unsigned char *data);
+// This function will determine the number of fonts in a font file.  TrueType
+// collection (.ttc) files may contain multiple fonts, while TrueType font
+// (.ttf) files only contain one font. The number of fonts can be used for
+// indexing with the previous function where the index is between zero and one
+// less than the total fonts. If an error occurs, -1 is returned.
+
 STBTT_DEF int stbtt_GetFontOffsetForIndex(const unsigned char *data, int index);
 // Each .ttf/.ttc file may have more than one font. Each font has a sequential
 // index number starting from 0. Call this function to get the font offset for
 // a given index; it returns -1 if the index is out of range. A regular .ttf
 // file will only define one font and it always be at offset 0, so it will
-// return '0' for index 0, and -1 for all other indices. You can just skip
-// this step if you know it's that kind of font.
-
+// return '0' for index 0, and -1 for all other indices.
 
 // The following structure is defined publically so you can declare one on
 // the stack or as a global or etc, but you should treat it as opaque.
@@ -1180,6 +1186,22 @@ static int stbtt_GetFontOffsetForIndex_internal(unsigned char *font_collection,
    return -1;
 }
 
+static int stbtt_GetNumberOfFonts_internal(unsigned char *font_collection)
+{
+   // if it's just a font, there's only one valid font
+   if (stbtt__isfont(font_collection))
+      return 1;
+
+   // check if it's a TTC
+   if (stbtt_tag(font_collection, "ttcf")) {
+      // version 1?
+      if (ttULONG(font_collection+4) == 0x00010000 || ttULONG(font_collection+4) == 0x00020000) {
+         return ttLONG(font_collection+8);
+      }
+   }
+   return 0;
+}
+
 static stbtt__buf stbtt__get_subrs(stbtt__buf cff, stbtt__buf fontdict)
 {
    stbtt_uint32 subrsoff = 0, private_loc[2] = { 0, 0 };
@@ -3918,6 +3940,11 @@ STBTT_DEF int stbtt_GetFontOffsetForIndex(const unsigned char *data, int index)
    return stbtt_GetFontOffsetForIndex_internal((unsigned char *) data, index);   
 }
 
+STBTT_DEF int stbtt_GetNumberOfFonts(const unsigned char *data)
+{
+   return stbtt_GetNumberOfFonts_internal((unsigned char *) data);
+}
+
 STBTT_DEF int stbtt_InitFont(stbtt_fontinfo *info, const unsigned char *data, int offset)
 {
    return stbtt_InitFont_internal(info, (unsigned char *) data, offset);