diff --git a/src/boot/types-ext.reb b/src/boot/types-ext.reb
index 4b0bc6d58b..7fa091d875 100644
--- a/src/boot/types-ext.reb
+++ b/src/boot/types-ext.reb
@@ -26,7 +26,7 @@ percent		*	64
 
 char		10	32
 pair		*	64
-tuple		*	64
+tuple		*	tuple
 time		*	64
 date		*	date
 
diff --git a/src/core/f-extension.c b/src/core/f-extension.c
index 0e74bea407..edd2be72b6 100644
--- a/src/core/f-extension.c
+++ b/src/core/f-extension.c
@@ -45,6 +45,7 @@ enum {
 	RXE_IMAGE,	// image
 	RXE_DATE,	// from upper section
 	RXE_OBJECT, // any object
+	RXE_TUPLE,  // 3-12 bytes tuple value
 	RXE_MAX
 };
 
@@ -113,6 +114,10 @@ x*/	RXIARG Value_To_RXI(REBVAL *val)
 		arg.width  = VAL_IMAGE_WIDE(val);
 		arg.height = VAL_IMAGE_HIGH(val);
 		break;
+	case RXE_TUPLE:
+		arg.tuple_len = VAL_TUPLE_LEN(val);
+		COPY_MEM(arg.tuple_bytes, VAL_TUPLE(val), MAX_TUPLE);
+		break;
 	case RXE_NULL:
 	default:
 		arg.int64 = 0;
@@ -161,6 +166,10 @@ x*/	void RXI_To_Value(REBVAL *val, RXIARG arg, REBCNT type)
 		VAL_IMAGE_WIDE(val) = arg.width;
 		VAL_IMAGE_HIGH(val) = arg.height;
 		break;
+	case RXE_TUPLE:
+		VAL_TUPLE_LEN(val) = arg.tuple_len;
+		COPY_MEM(VAL_TUPLE(val), arg.tuple_bytes, MAX_TUPLE);
+		break;
 	case RXE_NULL:
 		VAL_INT64(val) = 0;
 		break;
diff --git a/src/include/reb-ext.h b/src/include/reb-ext.h
index 03f9fb6a74..e6c3a0750a 100644
--- a/src/include/reb-ext.h
+++ b/src/include/reb-ext.h
@@ -42,6 +42,11 @@
 */
 
 // Value structure (for passing args to and from):
+// o: originaly (before 64bit) it was designed to fit to 8bytes
+// o: but tuple was still allowed to have 10 bytes, so one could not receive
+// o: all possible tuple values in the extension side!!
+// Now, when there can be stored all 12 allowed tuple bytes, the value must have 16bytes
+// on both (32 and 64bit) targets, so maximum number of arguments could be extended (from 7 to 15)
 #pragma pack(4)
 typedef union rxi_arg_val {
 	void *addr;
@@ -72,6 +77,12 @@ typedef union rxi_arg_val {
 		REBFLG flags:16;  // Handle_Flags
 		REBCNT index:16;  // Index into Reb_Handle_Spec value
 	} handle;
+	struct {
+		// keeping the same layout how it was before (first byte is size)
+		// there could probably be a more optimal way how to pass colors!
+		REBYTE tuple_len;
+		REBYTE tuple_bytes[MAX_TUPLE];
+	};
 } RXIARG;
 
 // For direct access to arg array:
@@ -108,7 +119,8 @@ typedef int (*RXICAL)(int cmd, RXIFRM *args, REBCEC *ctx);
 #define RXA_DATE(f,n)	(RXA_ARG(f,n).int32a)
 #define RXA_WORD(f,n)	(RXA_ARG(f,n).int32a)
 #define RXA_PAIR(f,n)	(RXA_ARG(f,n).pair)
-#define RXA_TUPLE(f,n)	(RXA_ARG(f,n).bytes)
+#define RXA_TUPLE(f,n)	(RXA_ARG(f,n).tuple_bytes)
+#define RXA_TUPLE_SIZE(f,n)	(RXA_ARG(f,n).tuple_size)
 #define RXA_SERIES(f,n)	(RXA_ARG(f,n).series)
 #define RXA_INDEX(f,n)	(RXA_ARG(f,n).index)
 #define RXA_OBJECT(f,n)	(RXA_ARG(f,n).addr)