diff --git a/src/filo.ads b/src/filo.ads
index 0ddc52c..21f1545 100644
--- a/src/filo.ads
+++ b/src/filo.ads
@@ -26,7 +26,7 @@
       Unsigned_16 (Buf (Buf'First + Off)))
    with
       Pre =>
-         Buf'First <= Index_Type16'Last - Off and
+         Buf'First <= Index_Type16'Last - Off and then
          Buf'First + Off + 1 <= Buf'Last;
 
    function Read_LE32 (Buf : Buffer_Type; Off : Index_Type32) return Unsigned_32
@@ -37,7 +37,7 @@
       Unsigned_32 (Buf (Buf'First + Off)))
    with
       Pre =>
-         Buf'First <= Index_Type32'Last - Off and
+         Buf'First <= Index_Type32'Last - Off and then
          Buf'First + Off + 3 <= Buf'Last;
 
    generic