diff --git a/btreeidx.cc b/btreeidx.cc
index bd8a3d07..cd6e5b18 100644
--- a/btreeidx.cc
+++ b/btreeidx.cc
@@ -49,7 +49,7 @@ using std::pair;
 enum
 {
   BtreeMinElements = 64,
-  BtreeMaxElements = 5120
+  BtreeMaxElements = 8192
 };
 
 BtreeIndex::BtreeIndex():
diff --git a/file.cc b/file.cc
index cbbc7035..12ddbdbb 100644
--- a/file.cc
+++ b/file.cc
@@ -239,7 +239,7 @@ std::string Class::gets( bool stripNl ) THROW_SPEC( exReadError, exWriteError )
   return std::string( buf );
 }
 
-void Class::seek( long offset ) THROW_SPEC( exSeekError, exWriteError )
+void Class::seek( qint64 offset ) THROW_SPEC( exSeekError, exWriteError )
 {
   if ( writeBuffer )
     flushWriteBuffer();
@@ -248,7 +248,7 @@ void Class::seek( long offset ) THROW_SPEC( exSeekError, exWriteError )
     throw exSeekError();
 }
 
-void Class::seekCur( long offset ) THROW_SPEC( exSeekError, exWriteError )
+void Class::seekCur( qint64 offset ) THROW_SPEC( exSeekError, exWriteError )
 {
   if ( writeBuffer )
     flushWriteBuffer();
@@ -257,7 +257,7 @@ void Class::seekCur( long offset ) THROW_SPEC( exSeekError, exWriteError )
     throw exSeekError();
 }
 
-void Class::seekEnd( long offset ) THROW_SPEC( exSeekError, exWriteError )
+void Class::seekEnd( qint64 offset ) THROW_SPEC( exSeekError, exWriteError )
 {
   if ( writeBuffer )
     flushWriteBuffer();
@@ -271,7 +271,7 @@ void Class::rewind() THROW_SPEC( exSeekError, exWriteError )
   seek( 0 );
 }
 
-size_t Class::tell() THROW_SPEC( exSeekError )
+qint64 Class::tell() THROW_SPEC( exSeekError )
 {
   qint64 result = f.pos();
 
@@ -281,7 +281,7 @@ size_t Class::tell() THROW_SPEC( exSeekError )
   if ( writeBuffer )
     result += ( WriteBufferSize - writeBufferLeft );
 
-  return ( size_t ) result;
+  return result;
 }
 
 bool Class::eof() THROW_SPEC( exWriteError )
diff --git a/file.hh b/file.hh
index 72e8b56d..5bcd2ec1 100644
--- a/file.hh
+++ b/file.hh
@@ -95,17 +95,17 @@ public:
   std::string gets( bool stripNl = true ) THROW_SPEC( exReadError, exWriteError );
 
   /// Seeks in the file, relative to its beginning.
-  void seek( long offset ) THROW_SPEC( exSeekError, exWriteError );
+  void seek( qint64 offset ) THROW_SPEC( exSeekError, exWriteError );
   /// Seeks in the file, relative to the current position.
-  void seekCur( long offset ) THROW_SPEC( exSeekError, exWriteError );
+  void seekCur( qint64 offset ) THROW_SPEC( exSeekError, exWriteError );
   /// Seeks in the file, relative to the end of file.
-  void seekEnd( long offset = 0 ) THROW_SPEC( exSeekError, exWriteError );
+  void seekEnd( qint64 offset = 0 ) THROW_SPEC( exSeekError, exWriteError );
 
   /// Seeks to the beginning of file
   void rewind() THROW_SPEC( exSeekError, exWriteError );
 
   /// Tells the current position within the file, relative to its beginning.
-  size_t tell() THROW_SPEC( exSeekError );
+  qint64 tell() THROW_SPEC( exSeekError );
 
   /// Returns true if end-of-file condition is set.
   bool eof() THROW_SPEC( exWriteError );