diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c
index 81b46585..2fc5cf2 100644
--- a/drivers/tty/n_gsm.c
+++ b/drivers/tty/n_gsm.c
@@ -716,8 +716,8 @@
 		if (msg->len < 128)
 			*--dp = (msg->len << 1) | EA;
 		else {
-			*--dp = ((msg->len & 127) << 1) | EA;
-			*--dp = (msg->len >> 6) & 0xfe;
+			*--dp = (msg->len >> 7);	/* bits 7 - 15 */
+			*--dp = (msg->len & 127) << 1;	/* bits 0 - 6 */
 		}
 	}