diff --git a/src/tag.rs b/src/tag.rs
index 005fcf5..5cd35fc 100644
--- a/src/tag.rs
+++ b/src/tag.rs
@@ -89,15 +89,13 @@ impl fmt::Display for Tag {
 #[derive(Debug, Copy, Clone, PartialEq, Eq)]
 pub enum Context {
     /// TIFF attributes defined in the TIFF Rev. 6.0 specification.
-    Tiff,	// 0th IFD
+    Tiff,	// 0th/1st IFD
     /// Exif attributes.
-    Exif,	// 0th IFD -- Exif IFD
+    Exif,	// 0th/1st IFD -- Exif IFD
     /// GPS attributes.
-    Gps,	// 0th IFD -- GPS IFD
+    Gps,	// 0th/1st IFD -- GPS IFD
     /// Interoperability attributes.
-    Interop,	// 0th IFD -- Exif IFD -- Interoperability IFD
-    /// TIFF fields in the 1st IFD, which represents the thumbnail image.
-    Thumb,	// 1st IFD
+    Interop,	// 0th/1st IFD -- Exif IFD -- Interoperability IFD
 }
 
 struct TagInfo {
@@ -149,7 +147,8 @@ generate_well_known_tag_constants!(
     /// structure of Exif data and will not be returned to the user.
     (InteropIFDPointer, 0xa005, "Interoperability IFD pointer"),
 
-    // TIFF attributes [EXIF23 4.6.4 Table 4 and 4.6.8 Table 17].
+    // TIFF primary and thumbnail attributes [EXIF23 4.6.4 Table 4,
+    // 4.6.8 Table 17, and 4.6.8 Table 21].
     |Context::Tiff|
 
     (ImageWidth, 0x100, "Image width"),
@@ -175,16 +174,14 @@ generate_well_known_tag_constants!(
     (Artist, 0x13b, "Person who created the image"),
     (WhitePoint, 0x13e, "White point chromaticity"),
     (PrimaryChromaticities, 0x13f, "Chromaticities of primaries"),
-    // (JPEGInterchangeFormat, 0x201, "Offset to JPEG SOI"),
-    // (JPEGInterchangeFormatLength, 0x202, "Bytes of JPEG data"),
+    (JPEGInterchangeFormat, 0x201, "Offset to JPEG SOI"),
+    (JPEGInterchangeFormatLength, 0x202, "Bytes of JPEG data"),
     (YCbCrCoefficients, 0x211, "Color space transformation matrix coefficients"),
     (YCbCrSubSampling, 0x212, "Subsampling ratio of Y to C"),
     (YCbCrPositioning, 0x213, "Y and C positioning"),
     (ReferenceBlackWhite, 0x214, "Pair of black and white reference values"),
     (Copyright, 0x8298, "Copyright holder"),
 
-    // Thumbnail Tiff attributes [EXIF23 4.6.4 Table 4 and 4.6.8 Table 21].
-
     // Exif IFD attributes [EXIF23 4.6.5 Table 7 and 4.6.8 Table 18].
     |Context::Exif|
 
diff --git a/src/tiff.rs b/src/tiff.rs
index eb027f6..c40ae24 100644
--- a/src/tiff.rs
+++ b/src/tiff.rs
@@ -39,7 +39,11 @@ const TIFF_FORTY_TWO: u16 = 0x002a;
 /// A TIFF field.
 #[derive(Debug)]
 pub struct Field<'a> {
+    /// The tag of this field.
     pub tag: Tag,
+    /// False for the primary image and true for the thumbnail.
+    pub thumbnail: bool,
+    /// The value of this field.
     pub value: Value<'a>,
 }
 
@@ -63,11 +67,11 @@ fn parse_exif_sub<E>(data: &[u8])
         return Err(Error::InvalidFormat("Invalid forty two"));
     }
     let ifd_offset = E::loadu32(data, 4) as usize;
-    parse_ifd::<E>(data, ifd_offset, Context::Tiff)
+    parse_ifd::<E>(data, ifd_offset, Context::Tiff, false)
 }
 
 // Parse IFD [EXIF23 4.6.2].
-fn parse_ifd<E>(data: &[u8], offset: usize, ctx: Context)
+fn parse_ifd<E>(data: &[u8], offset: usize, ctx: Context, thumbnail: bool)
                 -> Result<Vec<Field>, Error> where E: Endian {
     // Count (the number of the entries).
     if data.len() < offset || data.len() - offset < 2 {
@@ -108,16 +112,19 @@ fn parse_ifd<E>(data: &[u8], offset: usize, ctx: Context)
         // element of the field.
         let tag = Tag(ctx, tag);
         if tag == tag::ExifIFDPointer {
-            let mut v = try!(parse_ifd::<E>(data, ofs, Context::Exif));
+            let mut v = try!(
+                parse_ifd::<E>(data, ofs, Context::Exif, thumbnail));
             fields.append(&mut v);
         } else if tag == tag::GPSInfoIFDPointer {
-            let mut v = try!(parse_ifd::<E>(data, ofs, Context::Gps));
+            let mut v = try!(
+                parse_ifd::<E>(data, ofs, Context::Gps, thumbnail));
             fields.append(&mut v);
         } else if tag == tag::InteropIFDPointer {
-            let mut v = try!(parse_ifd::<E>(data, ofs, Context::Interop));
+            let mut v = try!(
+                parse_ifd::<E>(data, ofs, Context::Interop, thumbnail));
             fields.append(&mut v);
         } else {
-            fields.push(Field { tag: tag, value: val });
+            fields.push(Field { tag: tag, thumbnail: thumbnail, value: val });
         }
     }
 
@@ -127,11 +134,11 @@ fn parse_ifd<E>(data: &[u8], offset: usize, ctx: Context)
     }
     let next_ifd_offset = E::loadu32(data, offset + 2 + count * 12) as usize;
     if next_ifd_offset != 0 {
-        if ctx != Context::Tiff {
+        if ctx != Context::Tiff || thumbnail {
             return Err(Error::InvalidFormat("Unexpected next IFD"));
         }
         let mut v = try!(
-            parse_ifd::<E>(data, next_ifd_offset, Context::Thumb));
+            parse_ifd::<E>(data, next_ifd_offset, Context::Tiff, true));
         fields.append(&mut v);
     }