diff --git a/openbsc/include/openbsc/gsm_data_shared.h b/openbsc/include/openbsc/gsm_data_shared.h
index edc550e..0e5bc91 100644
--- a/openbsc/include/openbsc/gsm_data_shared.h
+++ b/openbsc/include/openbsc/gsm_data_shared.h
@@ -25,6 +25,7 @@
 #endif
 
 #include <openbsc/common_cs.h>
+#include <openbsc/rest_octets.h>
 
 struct osmo_bsc_data;
 
@@ -485,6 +486,7 @@
 	struct gsm_bts_trx_ts ts[TRX_NR_TS];
 };
 
+#define GSM_BTS_SI2Q(bts)	(struct gsm48_system_information_type_2quater *)((bts)->si_buf[SYSINFO_TYPE_2quater])
 #define GSM_BTS_SI(bts, i)	(void *)((bts)->si_buf[i])
 #define GSM_LCHAN_SI(lchan, i)	(void *)((lchan)->si.buf[i])
 
@@ -717,10 +719,13 @@
 	/* bitmask of all SI that are present/valid in si_buf */
 	uint32_t si_valid;
 	/* 3GPP TS 44.018 Table 10.5.2.33b.1 INDEX and COUNT for SI2quater */
-	uint8_t si2q_index;
-	uint8_t si2q_count;
+	uint8_t si2q_index; /* distinguish individual SI2quater messages */
+	uint8_t si2q_count; /* si2q_index for the last (highest indexed) individual SI2quater message */
 	/* buffers where we put the pre-computed SI */
 	sysinfo_buf_t si_buf[_MAX_SYSINFO_TYPE];
+	/* offsets used while generating SI2quater */
+	size_t e_offset;
+	size_t u_offset;
 
 	/* ip.accesss Unit ID's have Site/BTS/TRX layout */
 	union {
diff --git a/openbsc/include/openbsc/rest_octets.h b/openbsc/include/openbsc/rest_octets.h
index 73ce57b..7b324d3 100644
--- a/openbsc/include/openbsc/rest_octets.h
+++ b/openbsc/include/openbsc/rest_octets.h
@@ -13,8 +13,7 @@
 
 /* generate SI1 rest octets */
 int rest_octets_si1(uint8_t *data, uint8_t *nch_pos, int is1800_net);
-int rest_octets_si2quater(uint8_t *data, uint8_t index, uint8_t count, const struct osmo_earfcn_si2q *e,
-			  const uint16_t *u, const uint16_t *sc, size_t u_len);
+int rest_octets_si2quater(uint8_t *data, struct gsm_bts *bts);
 int rest_octets_si6(uint8_t *data, bool is1800_net);
 
 struct gsm48_si_selection_params {
diff --git a/openbsc/include/openbsc/system_information.h b/openbsc/include/openbsc/system_information.h
index b012107..21016b8 100644
--- a/openbsc/include/openbsc/system_information.h
+++ b/openbsc/include/openbsc/system_information.h
@@ -8,13 +8,12 @@
 struct gsm_bts;
 
 int gsm_generate_si(struct gsm_bts *bts, enum osmo_sysinfo_type type);
-unsigned uarfcn_size(const uint16_t *u, const uint16_t *sc, size_t u_len);
-unsigned earfcn_size(const struct osmo_earfcn_si2q *e);
+size_t si2q_earfcn_count(const struct osmo_earfcn_si2q *e);
 unsigned range1024_p(unsigned n);
 unsigned range512_q(unsigned m);
 int range_encode(enum gsm48_range r, int *arfcns, int arfcns_used, int *w,
 		 int f0, uint8_t *chan_list);
-uint8_t si2q_num(const struct gsm_bts *bts);
+uint8_t si2q_num(struct gsm_bts *bts);
 int bts_uarfcn_del(struct gsm_bts *bts, uint16_t arfcn, uint16_t scramble);
 int bts_uarfcn_add(struct gsm_bts *bts, uint16_t arfcn, uint16_t scramble,
 		   bool diversity);