diff --git a/io_posix.cpp b/io_posix.cpp
index f584b1c7..bea0b7b8 100644
--- a/io_posix.cpp
+++ b/io_posix.cpp
@@ -63,14 +63,20 @@ mapped_file::load_fd (int mflags) {
 
 //----------------------------------------------------------------------------
 size_t
-mapped_file::size (void) const {
-    CHECK (m_size > 0);
-    CHECK (m_data != NULL);
-
+mapped_file::size (void) const
+{
     return m_size;
 }
 
 
+//-----------------------------------------------------------------------------
+bool
+mapped_file::empty (void) const
+{
+    return size () == 0;
+}
+
+
 //----------------------------------------------------------------------------
 uint8_t*
 mapped_file::data (void) {
diff --git a/io_posix.hpp b/io_posix.hpp
index 781b82d8..e62d6e0b 100644
--- a/io_posix.hpp
+++ b/io_posix.hpp
@@ -42,7 +42,9 @@ namespace util {
 
                 const uint8_t* data (void) const;
                 uint8_t*       data (void);
-                size_t         size (void) const;
+
+                bool empty (void) const;
+                size_t size (void) const;
 
                 uint8_t*       begin (void);
                 uint8_t*       end   (void);