diff --git a/library/md4.c b/library/md4.c
index a1c8244..ad52e5e 100644
--- a/library/md4.c
+++ b/library/md4.c
@@ -285,7 +285,7 @@
     unsigned char buf[1024];
 
     if( ( f = fopen( path, "rb" ) ) == NULL )
-        return( 1 );
+        return( POLARSSL_ERR_MD4_FILE_IO_ERROR );
 
     md4_starts( &ctx );
 
@@ -299,7 +299,7 @@
     if( ferror( f ) != 0 )
     {
         fclose( f );
-        return( 2 );
+        return( POLARSSL_ERR_MD4_FILE_IO_ERROR );
     }
 
     fclose( f );