diff --git a/include/qubes-gui-protocol.h b/include/qubes-gui-protocol.h
index 1bf5fcf..95f7d83 100644
--- a/include/qubes-gui-protocol.h
+++ b/include/qubes-gui-protocol.h
@@ -55,6 +55,11 @@
  *  - gui-daemon sends MSG_WINDOW_DUMP_ACK to acknowledge finishing
  *    MSG_WINDOW_DUMP processing; this allows agent to know when it
  *    can safely unmap a window's grants
+ * 1.8:
+ *  - agent could send up to 256KB of clipboard data. And if clipboard is over
+ *    the limit, it will send one byte over it to trigger rejection on xside.
+ *    xside actual maximum (from 256B to 256KB) is user configurable. Anything
+ *    over it will raise an error and triggers a visual notification to user.
  */
 
 
@@ -67,7 +72,7 @@ typedef unsigned __int32 uint32_t;
 /* version of protocol described in this file, used as gui-daemon protocol
  * version; specific agent defines own version which them support */
 #define QUBES_GUID_PROTOCOL_VERSION_MAJOR 1
-#define QUBES_GUID_PROTOCOL_VERSION_MINOR 7
+#define QUBES_GUID_PROTOCOL_VERSION_MINOR 8
 #define QUBES_GUID_PROTOCOL_VERSION (QUBES_GUID_PROTOCOL_VERSION_MAJOR << 16 | QUBES_GUID_PROTOCOL_VERSION_MINOR)
 
 /* Before this version, MSG_CLIPBOARD_DATA passed the length in the window field */
@@ -82,8 +87,11 @@ typedef unsigned __int32 uint32_t;
 /* Minimum version for MSG_WINDOW_DUMP_ACK */
 #define QUBES_GUID_MIN_MSG_WINDOW_DUMP_ACK 0x00010007
 
+/* Minimum version for (up to) 4x sized clipboard */
+#define QUBES_GUID_MIN_CLIPBOARD_4X 0x00010008
+
 //arbitrary
-#define MAX_CLIPBOARD_SIZE 65000
+#define MAX_CLIPBOARD_SIZE 256000
 #define MAX_WINDOW_WIDTH 16384
 #define MAX_WINDOW_HEIGHT 6144
 
diff --git a/version b/version
index df0228d..d6f85ab 100644
--- a/version
+++ b/version
@@ -1 +1 @@
-4.2.5
+4.2.6