diff --git a/openbsc/src/gsm_04_11.c b/openbsc/src/gsm_04_11.c
index 246847bf2..e1b417a86 100644
--- a/openbsc/src/gsm_04_11.c
+++ b/openbsc/src/gsm_04_11.c
@@ -276,6 +276,7 @@ static int gsm340_gen_tpdu(struct msgb *msg, struct gsm_sms *sms)
 	u_int8_t *smsp;
 	u_int8_t oa[12];	/* max len per 03.40 */
 	u_int8_t oa_len = 0;
+	u_int8_t octet_len;
 	unsigned int old_msg_len = msg->len;
 
 	/* generate first octet with masked bits */
@@ -321,10 +322,13 @@ static int gsm340_gen_tpdu(struct msgb *msg, struct gsm_sms *sms)
 	/* generate TP-UD */
 	/* FIXME: Handle DSC of UCS2 or 8/bit default */
 	if (gsm338_get_sms_alphabet(sms->data_coding_scheme) == DCS_7BIT_DEFAULT) {
+		octet_len = sms->user_data_len*7/8;
+		if (sms->user_data_len*7%8 != 0)
+			octet_len++;
 		/* Warning, user_data_len indicates the amount of septets
 		 * (characters), we need amount of octets occupied */
-		smsp = msgb_put(msg, ceil(sms->user_data_len*7/8.0));
-		memcpy(smsp, sms->user_data, ceil(sms->user_data_len*7/8.0));
+		smsp = msgb_put(msg, octet_len);
+		memcpy(smsp, sms->user_data, octet_len);
 	}
 
 	return msg->len - old_msg_len;