diff --git a/src/filo-blockdev.ads b/src/filo-blockdev.ads
index 2fde36a..0233f88 100644
--- a/src/filo-blockdev.ads
+++ b/src/filo-blockdev.ads
@@ -4,7 +4,7 @@
 package FILO.Blockdev is
 
    Procedure Read
-      (Buffer  : in out Buffer_Type;
+      (Buffer  :    out Buffer_Type;
        Offset  : in     Blockdev_Offset;
        Success :    out Boolean)
    with