diff --git a/src/mp4box/avc1.rs b/src/mp4box/avc1.rs
index bc11ef5..27f428e 100644
--- a/src/mp4box/avc1.rs
+++ b/src/mp4box/avc1.rs
@@ -72,7 +72,7 @@ impl<R: Read + Seek> ReadBox<&mut R> for Avc1Box {
         let vertresolution = FixedPointU16::new_raw(reader.read_u32::<BigEndian>()?);
         reader.read_u32::<BigEndian>()?; // reserved
         let frame_count = reader.read_u16::<BigEndian>()?;
-        skip_read(reader, 32)?; // compressorname
+        skip_bytes(reader, 32)?; // compressorname
         let depth = reader.read_u16::<BigEndian>()?;
         reader.read_i16::<BigEndian>()?; // pre-defined
 
@@ -81,7 +81,7 @@ impl<R: Read + Seek> ReadBox<&mut R> for Avc1Box {
         if name == BoxType::AvcCBox {
             let avcc = AvcCBox::read_box(reader, s)?;
 
-            skip_read_to(reader, start + size)?;
+            skip_bytes_to(reader, start + size)?;
 
             Ok(Avc1Box {
                 data_reference_index,
@@ -118,7 +118,7 @@ impl<W: Write> WriteBox<&mut W> for Avc1Box {
         writer.write_u32::<BigEndian>(0)?; // reserved
         writer.write_u16::<BigEndian>(self.frame_count)?;
         // skip compressorname
-        skip_write(writer, 32)?;
+        write_zeros(writer, 32)?;
         writer.write_u16::<BigEndian>(self.depth)?;
         writer.write_i16::<BigEndian>(-1)?; // pre-defined
 
@@ -192,7 +192,7 @@ impl<R: Read + Seek> ReadBox<&mut R> for AvcCBox {
             picture_parameter_sets.push(nal_unit);
         }
 
-        skip_read_to(reader, start + size)?;
+        skip_bytes_to(reader, start + size)?;
 
         Ok(AvcCBox {
             configuration_version,
diff --git a/src/mp4box/co64.rs b/src/mp4box/co64.rs
index c425b4c..511db77 100644
--- a/src/mp4box/co64.rs
+++ b/src/mp4box/co64.rs
@@ -33,7 +33,7 @@ impl<R: Read + Seek> ReadBox<&mut R> for Co64Box {
             entries.push(chunk_offset);
         }
 
-        skip_read_to(reader, start + size)?;
+        skip_bytes_to(reader, start + size)?;
 
         Ok(Co64Box {
             version,
diff --git a/src/mp4box/ctts.rs b/src/mp4box/ctts.rs
index c3ee0c3..49d666a 100644
--- a/src/mp4box/ctts.rs
+++ b/src/mp4box/ctts.rs
@@ -42,7 +42,7 @@ impl<R: Read + Seek> ReadBox<&mut R> for CttsBox {
             entries.push(entry);
         }
 
-        skip_read_to(reader, start + size)?;
+        skip_bytes_to(reader, start + size)?;
 
         Ok(CttsBox {
             version,
diff --git a/src/mp4box/edts.rs b/src/mp4box/edts.rs
index 4eb1842..c36b59c 100644
--- a/src/mp4box/edts.rs
+++ b/src/mp4box/edts.rs
@@ -45,7 +45,7 @@ impl<R: Read + Seek> ReadBox<&mut R> for EdtsBox {
             _ => {}
         }
 
-        skip_read_to(reader, start + size)?;
+        skip_bytes_to(reader, start + size)?;
 
         Ok(edts)
     }
diff --git a/src/mp4box/elst.rs b/src/mp4box/elst.rs
index 75e29a4..ecd1d32 100644
--- a/src/mp4box/elst.rs
+++ b/src/mp4box/elst.rs
@@ -65,7 +65,7 @@ impl<R: Read + Seek> ReadBox<&mut R> for ElstBox {
             entries.push(entry);
         }
 
-        skip_read_to(reader, start + size)?;
+        skip_bytes_to(reader, start + size)?;
 
         Ok(ElstBox {
             version,
diff --git a/src/mp4box/ftyp.rs b/src/mp4box/ftyp.rs
index fc8d132..418f3a0 100644
--- a/src/mp4box/ftyp.rs
+++ b/src/mp4box/ftyp.rs
@@ -37,7 +37,7 @@ impl<R: Read + Seek> ReadBox<&mut R> for FtypBox {
             brands.push(From::from(b));
         }
 
-        skip_read_to(reader, start + size)?;
+        skip_bytes_to(reader, start + size)?;
 
         Ok(FtypBox {
             major_brand: From::from(major),
diff --git a/src/mp4box/hdlr.rs b/src/mp4box/hdlr.rs
index 178f223..a7bf34b 100644
--- a/src/mp4box/hdlr.rs
+++ b/src/mp4box/hdlr.rs
@@ -30,7 +30,7 @@ impl<R: Read + Seek> ReadBox<&mut R> for HdlrBox {
         reader.read_u32::<BigEndian>()?; // pre-defined
         let handler = reader.read_u32::<BigEndian>()?;
 
-        skip_read(reader, 12)?; // reserved
+        skip_bytes(reader, 12)?; // reserved
 
         let buf_size = size - HEADER_SIZE - HEADER_EXT_SIZE - 20 - 1;
         let mut buf = vec![0u8; buf_size as usize];
@@ -44,7 +44,7 @@ impl<R: Read + Seek> ReadBox<&mut R> for HdlrBox {
             _ => String::from("null"),
         };
 
-        skip_read_to(reader, start + size)?;
+        skip_bytes_to(reader, start + size)?;
 
         Ok(HdlrBox {
             version,
diff --git a/src/mp4box/mdhd.rs b/src/mp4box/mdhd.rs
index 67ef558..5e53982 100644
--- a/src/mp4box/mdhd.rs
+++ b/src/mp4box/mdhd.rs
@@ -73,7 +73,7 @@ impl<R: Read + Seek> ReadBox<&mut R> for MdhdBox {
         let language_code = reader.read_u16::<BigEndian>()?;
         let language = language_string(language_code);
 
-        skip_read_to(reader, start + size)?;
+        skip_bytes_to(reader, start + size)?;
 
         Ok(MdhdBox {
             version,
diff --git a/src/mp4box/mdia.rs b/src/mp4box/mdia.rs
index 92914b0..cf7ff07 100644
--- a/src/mp4box/mdia.rs
+++ b/src/mp4box/mdia.rs
@@ -64,7 +64,7 @@ impl<R: Read + Seek> ReadBox<&mut R> for MdiaBox {
             return Err(Error::BoxNotFound(BoxType::MinfBox));
         }
 
-        skip_read_to(reader, start + size)?;
+        skip_bytes_to(reader, start + size)?;
 
         Ok(MdiaBox {
             mdhd: mdhd.unwrap(),
diff --git a/src/mp4box/minf.rs b/src/mp4box/minf.rs
index f20f9ab..0da39a9 100644
--- a/src/mp4box/minf.rs
+++ b/src/mp4box/minf.rs
@@ -70,7 +70,7 @@ impl<R: Read + Seek> ReadBox<&mut R> for MinfBox {
             return Err(Error::BoxNotFound(BoxType::StblBox));
         }
 
-        skip_read_to(reader, start + size)?;
+        skip_bytes_to(reader, start + size)?;
 
         Ok(MinfBox {
             vmhd,
diff --git a/src/mp4box/mod.rs b/src/mp4box/mod.rs
index 8367e4b..0721e2c 100644
--- a/src/mp4box/mod.rs
+++ b/src/mp4box/mod.rs
@@ -180,28 +180,27 @@ pub fn write_box_header_ext<W: Write>(w: &mut W, v: u8, f: u32) -> Result<u64> {
     Ok(4)
 }
 
-pub fn box_start<R: Seek>(reader: &mut R) -> Result<u64> {
-    Ok(reader.seek(SeekFrom::Current(0))? - HEADER_SIZE)
+pub fn box_start<R: Seek>(seeker: &mut R) -> Result<u64> {
+    Ok(seeker.seek(SeekFrom::Current(0))? - HEADER_SIZE)
 }
 
-pub fn skip_read<R: Read + Seek>(reader: &mut R, size: i64) -> Result<()> {
-    assert!(size >= 0);
-    reader.seek(SeekFrom::Current(size))?;
+pub fn skip_bytes<S: Seek>(seeker: &mut S, size: u64) -> Result<()> {
+    seeker.seek(SeekFrom::Current(size as i64))?;
     Ok(())
 }
 
-pub fn skip_read_to<R: Read + Seek>(reader: &mut R, pos: u64) -> Result<()> {
-    reader.seek(SeekFrom::Start(pos))?;
+pub fn skip_bytes_to<S: Seek>(seeker: &mut S, pos: u64) -> Result<()> {
+    seeker.seek(SeekFrom::Start(pos))?;
     Ok(())
 }
 
-pub fn skip_box<R: Read + Seek>(reader: &mut R, size: u64) -> Result<()> {
-    let start = box_start(reader)?;
-    skip_read_to(reader, start + size)?;
+pub fn skip_box<S: Seek>(seeker: &mut S, size: u64) -> Result<()> {
+    let start = box_start(seeker)?;
+    skip_bytes_to(seeker, start + size)?;
     Ok(())
 }
 
-pub fn skip_write<W: Write>(writer: &mut W, size: u64) -> Result<()> {
+pub fn write_zeros<W: Write>(writer: &mut W, size: u64) -> Result<()> {
     for _ in 0..size {
         writer.write_u8(0)?;
     }
diff --git a/src/mp4box/moov.rs b/src/mp4box/moov.rs
index 218dc5a..045440e 100644
--- a/src/mp4box/moov.rs
+++ b/src/mp4box/moov.rs
@@ -62,7 +62,7 @@ impl<R: Read + Seek> ReadBox<&mut R> for MoovBox {
             return Err(Error::BoxNotFound(BoxType::MvhdBox));
         }
 
-        skip_read_to(reader, start + size)?;
+        skip_bytes_to(reader, start + size)?;
 
         Ok(MoovBox {
             mvhd: mvhd.unwrap(),
diff --git a/src/mp4box/mp4a.rs b/src/mp4box/mp4a.rs
index f6ac5f3..081f926 100644
--- a/src/mp4box/mp4a.rs
+++ b/src/mp4box/mp4a.rs
@@ -65,7 +65,7 @@ impl<R: Read + Seek> ReadBox<&mut R> for Mp4aBox {
         if name == BoxType::EsdsBox {
             let esds = EsdsBox::read_box(reader, s)?;
 
-            skip_read_to(reader, start + size)?;
+            skip_bytes_to(reader, start + size)?;
 
             Ok(Mp4aBox {
                 data_reference_index,
@@ -153,7 +153,7 @@ impl<R: Read + Seek> ReadBox<&mut R> for EsdsBox {
             return Err(Error::InvalidData("ESDescriptor not found"));
         }
 
-        skip_read_to(reader, start + size)?;
+        skip_bytes_to(reader, start + size)?;
 
         Ok(EsdsBox {
             version,
@@ -285,7 +285,7 @@ impl<R: Read + Seek> ReadDesc<&mut R> for ESDescriptor {
                     sl_config = Some(SLConfigDescriptor::read_desc(reader, desc_size)?);
                 }
                 _ => {
-                    skip_read(reader, desc_size as i64 - 1)?;
+                    skip_bytes(reader, desc_size as u64 - 1)?;
                 }
             }
             current = reader.seek(SeekFrom::Current(0))?;
@@ -378,7 +378,7 @@ impl<R: Read + Seek> ReadDesc<&mut R> for DecoderConfigDescriptor {
                     dec_specific = Some(DecoderSpecificDescriptor::read_desc(reader, desc_size)?);
                 }
                 _ => {
-                    skip_read(reader, desc_size as i64 - 1)?;
+                    skip_bytes(reader, desc_size as u64 - 1)?;
                 }
             }
             current = reader.seek(SeekFrom::Current(0))?;
diff --git a/src/mp4box/mvhd.rs b/src/mp4box/mvhd.rs
index 909ab7d..bd38fbf 100644
--- a/src/mp4box/mvhd.rs
+++ b/src/mp4box/mvhd.rs
@@ -70,7 +70,7 @@ impl<R: Read + Seek> ReadBox<&mut R> for MvhdBox {
         };
         let rate = FixedPointU16::new_raw(reader.read_u32::<BigEndian>()?);
 
-        skip_read_to(reader, start + size)?;
+        skip_bytes_to(reader, start + size)?;
 
         Ok(MvhdBox {
             version,
@@ -106,7 +106,7 @@ impl<W: Write> WriteBox<&mut W> for MvhdBox {
         writer.write_u32::<BigEndian>(self.rate.raw_value())?;
 
         // XXX volume, ...
-        skip_write(writer, 76)?;
+        write_zeros(writer, 76)?;
 
         Ok(size)
     }
diff --git a/src/mp4box/smhd.rs b/src/mp4box/smhd.rs
index 5f80ddb..3879a18 100644
--- a/src/mp4box/smhd.rs
+++ b/src/mp4box/smhd.rs
@@ -38,7 +38,7 @@ impl<R: Read + Seek> ReadBox<&mut R> for SmhdBox {
 
         let balance = FixedPointI8::new_raw(reader.read_i16::<BigEndian>()?);
 
-        skip_read_to(reader, start + size)?;
+        skip_bytes_to(reader, start + size)?;
 
         Ok(SmhdBox {
             version,
diff --git a/src/mp4box/stbl.rs b/src/mp4box/stbl.rs
index 4236f64..8f7db65 100644
--- a/src/mp4box/stbl.rs
+++ b/src/mp4box/stbl.rs
@@ -114,7 +114,7 @@ impl<R: Read + Seek> ReadBox<&mut R> for StblBox {
             return Err(Error::Box2NotFound(BoxType::StcoBox, BoxType::Co64Box));
         }
 
-        skip_read_to(reader, start + size)?;
+        skip_bytes_to(reader, start + size)?;
 
         Ok(StblBox {
             stsd: stsd.unwrap(),
diff --git a/src/mp4box/stco.rs b/src/mp4box/stco.rs
index e6822c1..301cb50 100644
--- a/src/mp4box/stco.rs
+++ b/src/mp4box/stco.rs
@@ -33,7 +33,7 @@ impl<R: Read + Seek> ReadBox<&mut R> for StcoBox {
             entries.push(chunk_offset);
         }
 
-        skip_read_to(reader, start + size)?;
+        skip_bytes_to(reader, start + size)?;
 
         Ok(StcoBox {
             version,
diff --git a/src/mp4box/stsc.rs b/src/mp4box/stsc.rs
index e712646..fe83cc7 100644
--- a/src/mp4box/stsc.rs
+++ b/src/mp4box/stsc.rs
@@ -59,7 +59,7 @@ impl<R: Read + Seek> ReadBox<&mut R> for StscBox {
             }
         }
 
-        skip_read_to(reader, start + size)?;
+        skip_bytes_to(reader, start + size)?;
 
         Ok(StscBox {
             version,
diff --git a/src/mp4box/stsd.rs b/src/mp4box/stsd.rs
index f83667e..5731c7f 100644
--- a/src/mp4box/stsd.rs
+++ b/src/mp4box/stsd.rs
@@ -53,7 +53,7 @@ impl<R: Read + Seek> ReadBox<&mut R> for StsdBox {
             _ => {}
         }
 
-        skip_read_to(reader, start + size)?;
+        skip_bytes_to(reader, start + size)?;
 
         Ok(StsdBox {
             version,
diff --git a/src/mp4box/stss.rs b/src/mp4box/stss.rs
index 422c975..412174b 100644
--- a/src/mp4box/stss.rs
+++ b/src/mp4box/stss.rs
@@ -33,7 +33,7 @@ impl<R: Read + Seek> ReadBox<&mut R> for StssBox {
             entries.push(sample_number);
         }
 
-        skip_read_to(reader, start + size)?;
+        skip_bytes_to(reader, start + size)?;
 
         Ok(StssBox {
             version,
diff --git a/src/mp4box/stsz.rs b/src/mp4box/stsz.rs
index 41c1663..99a4de6 100644
--- a/src/mp4box/stsz.rs
+++ b/src/mp4box/stsz.rs
@@ -38,7 +38,7 @@ impl<R: Read + Seek> ReadBox<&mut R> for StszBox {
             }
         }
 
-        skip_read_to(reader, start + size)?;
+        skip_bytes_to(reader, start + size)?;
 
         Ok(StszBox {
             version,
diff --git a/src/mp4box/stts.rs b/src/mp4box/stts.rs
index 5a01f82..8ca673f 100644
--- a/src/mp4box/stts.rs
+++ b/src/mp4box/stts.rs
@@ -42,7 +42,7 @@ impl<R: Read + Seek> ReadBox<&mut R> for SttsBox {
             entries.push(entry);
         }
 
-        skip_read_to(reader, start + size)?;
+        skip_bytes_to(reader, start + size)?;
 
         Ok(SttsBox {
             version,
diff --git a/src/mp4box/tkhd.rs b/src/mp4box/tkhd.rs
index ff3119b..effe5c2 100644
--- a/src/mp4box/tkhd.rs
+++ b/src/mp4box/tkhd.rs
@@ -124,7 +124,7 @@ impl<R: Read + Seek> ReadBox<&mut R> for TkhdBox {
         let width = FixedPointU16::new_raw(reader.read_u32::<BigEndian>()?);
         let height = FixedPointU16::new_raw(reader.read_u32::<BigEndian>()?);
 
-        skip_read_to(reader, start + size)?;
+        skip_bytes_to(reader, start + size)?;
 
         Ok(TkhdBox {
             version,
diff --git a/src/mp4box/trak.rs b/src/mp4box/trak.rs
index e92683a..30e0353 100644
--- a/src/mp4box/trak.rs
+++ b/src/mp4box/trak.rs
@@ -67,7 +67,7 @@ impl<R: Read + Seek> ReadBox<&mut R> for TrakBox {
             return Err(Error::BoxNotFound(BoxType::MdiaBox));
         }
 
-        skip_read_to(reader, start + size)?;
+        skip_bytes_to(reader, start + size)?;
 
         Ok(TrakBox {
             tkhd: tkhd.unwrap(),
diff --git a/src/mp4box/vmhd.rs b/src/mp4box/vmhd.rs
index 45e420d..623c2ff 100644
--- a/src/mp4box/vmhd.rs
+++ b/src/mp4box/vmhd.rs
@@ -41,7 +41,7 @@ impl<R: Read + Seek> ReadBox<&mut R> for VmhdBox {
             blue: reader.read_u16::<BigEndian>()?,
         };
 
-        skip_read_to(reader, start + size)?;
+        skip_bytes_to(reader, start + size)?;
 
         Ok(VmhdBox {
             version,