diff --git a/src/jtag/jlink.c b/src/jtag/jlink.c
index 8626b18cd..1269fa846 100644
--- a/src/jtag/jlink.c
+++ b/src/jtag/jlink.c
@@ -672,7 +672,7 @@ static int jlink_tap_execute(void)
 		return ERROR_OK;
 
 	// number of full bytes (plus one if some would be left over)
-	byte_length = tap_length / 8 + !!(tap_length % 8);
+	byte_length = TAP_SCAN_BYTES(tap_length);
 
 	usb_out_buffer[0] = EMU_CMD_HW_JTAG3;
 	usb_out_buffer[1] = 0;
diff --git a/src/jtag/jtag.h b/src/jtag/jtag.h
index 2a7d85615..a14edb481 100644
--- a/src/jtag/jtag.h
+++ b/src/jtag/jtag.h
@@ -217,6 +217,9 @@ typedef void* error_handler_t;  /* Later on we can delete error_handler_t, but k
 struct scan_field_s;
 typedef int (*in_handler_t)(u8* in_value, void* priv, struct scan_field_s* field);
 
+/// @brief calculates number of bytes required to hold @a n TAP scan bits
+#define TAP_SCAN_BYTES(n)		(((n) / 8) + !!((n) % 8))
+
 typedef struct scan_field_s
 {
 	jtag_tap_t* tap;                /* tap pointer this instruction refers to */