diff --git a/src/mp4file.cpp b/src/mp4file.cpp
index 73772a7..217e388 100644
--- a/src/mp4file.cpp
+++ b/src/mp4file.cpp
@@ -417,8 +417,7 @@
 
 void MP4File::ReadFromFile()
 {
-    // ensure we start at beginning of file or at specified seek offset.
-    SetPosition(m_initialSeekOffset);
+    SetPosition(0);
 
     // create a new root atom
     ASSERT(m_pRootAtom == NULL);
diff --git a/src/mp4file_io.cpp b/src/mp4file_io.cpp
index d16d87f..acbc3d2 100644
--- a/src/mp4file_io.cpp
+++ b/src/mp4file_io.cpp
@@ -37,7 +37,7 @@
         file = m_file;
 
     ASSERT( file );
-    return file->position;
+    return file->position - m_initialSeekOffset;
 }
 
 void MP4File::SetPosition( uint64_t pos, File* file )
@@ -53,7 +53,7 @@
         file = m_file;
 
     ASSERT( file );
-    if( file->seek( pos ))
+    if( file->seek( pos + m_initialSeekOffset))
         throw new PlatformException( "seek failed", sys::getLastError(), __FILE__, __LINE__, __FUNCTION__ );
 }
 
@@ -66,7 +66,7 @@
         file = m_file;
 
     ASSERT( file );
-    return file->size;
+    return file->size - m_initialSeekOffset;
 }
 
 void MP4File::ReadBytes( uint8_t* buf, uint32_t bufsiz, File* file )