diff --git a/src/filo-blockdev.adb b/src/filo-blockdev.adb
index 5bb6732..44f79bd 100644
--- a/src/filo-blockdev.adb
+++ b/src/filo-blockdev.adb
@@ -4,6 +4,8 @@
       (Buffer  : in out Buffer_Type;
        Offset  : in     Blockdev_Offset;
        Success :    out Boolean)
+   with
+      SPARK_Mode => Off
    is
       use Interfaces.C;