diff --git a/include/polarssl/sha4.h b/include/polarssl/sha4.h
index 06a85f1..dafebec 100644
--- a/include/polarssl/sha4.h
+++ b/include/polarssl/sha4.h
@@ -29,6 +29,8 @@
 
 #include <string.h>
 
+#define POLARSSL_ERR_SHA4_FILE_IO_ERROR                -0x007A  /**< Read/write error in file. */
+
 #if defined(_MSC_VER) || defined(__WATCOMC__)
   #define UL64(x) x##ui64
   #define long64 __int64
@@ -99,8 +101,7 @@
  * \param output   SHA-384/512 checksum result
  * \param is384    0 = use SHA512, 1 = use SHA384
  *
- * \return         0 if successful, 1 if fopen failed,
- *                 or 2 if fread failed
+ * \return         0 if successful, or POLARSSL_ERR_SHA4_FILE_IO_ERROR
  */
 int sha4_file( const char *path, unsigned char output[64], int is384 );