diff --git a/archive_reader_entry_buffer.cpp b/archive_reader_entry_buffer.cpp
index b7f0253..3a8dad4 100644
--- a/archive_reader_entry_buffer.cpp
+++ b/archive_reader_entry_buffer.cpp
@@ -43,7 +43,7 @@ int entry_buffer::underflow()
 {
   if(gptr() == egptr())
   {
-    size_t _buff_size = archive_read_data(_archive, _buff, _buff_max_size);
+    ssize_t _buff_size = archive_read_data(_archive, _buff, _buff_max_size);
 
     if( _buff_size < 0 )
     {