diff --git a/libburn/os-freebsd.h b/libburn/os-freebsd.h
index 21b4b97..0c1aaff 100644
--- a/libburn/os-freebsd.h
+++ b/libburn/os-freebsd.h
@@ -44,7 +44,8 @@ SIGKILL, SIGCHLD, SIGSTOP, SIGURG
 
 
 /* The maximum size for a (SCSI) i/o transaction */
-#define BURN_OS_TRANSPORT_BUFFER_SIZE 65536/2
+/* Important : MUST be at least 32768 ! */
+#define BURN_OS_TRANSPORT_BUFFER_SIZE 32768
 
 
 /** To hold all state information of BSD device enumeration
diff --git a/libburn/os-linux.h b/libburn/os-linux.h
index 3254191..0fc7c1e 100644
--- a/libburn/os-linux.h
+++ b/libburn/os-linux.h
@@ -41,6 +41,7 @@ SIGKILL, SIGCHLD, SIGSTOP, SIGURG
 
 
 /* The maximum size for a (SCSI) i/o transaction */
+/* Important : MUST be at least 32768 ! */
 #define BURN_OS_TRANSPORT_BUFFER_SIZE 65536