diff --git a/src/gsm/gsm48_rest_octets.c b/src/gsm/gsm48_rest_octets.c
index 84b7589..5c7d77a 100644
--- a/src/gsm/gsm48_rest_octets.c
+++ b/src/gsm/gsm48_rest_octets.c
@@ -165,7 +165,7 @@
 {
 	bool appended;
 	unsigned int old = bv->cur_bit; /* save current position to make rollback possible */
-	int rem = budget - 25;
+	int rem = ((int)budget) - 40;
 	if (rem <= 0)
 		return;
 
@@ -193,6 +193,8 @@
 	/* Priority and E-UTRAN Parameters Description */
 	bitvec_set_bit(bv, 1);
 
+	/* budget: 10 bits used above */
+
 	/* Serving Cell Priority Parameters Descr. is Present,
 	* see also: 3GPP TS 44.018, Table 10.5.2.33b.1 */
 	bitvec_set_bit(bv, 1);
@@ -212,6 +214,8 @@
 	/* T_Reselection */
 	bitvec_set_uint(bv, 0, 2);
 
+	/* budget: 26 bits used above */
+
 	/* No 3G Priority Parameters Description */
 	bitvec_set_bit(bv, 0);
 	/* E-UTRAN Parameters Description */
@@ -235,12 +239,16 @@
 	/* Repeated E-UTRAN Neighbour Cells */
 	bitvec_set_bit(bv, 1);
 
+	/* budget: 34 bits used above */
+
 	appended = append_eutran_neib_cell(bv, e, e_offset, rem);
 	if (!appended) { /* appending is impossible within current budget: rollback */
 		bv->cur_bit = old;
 		return;
 	}
 
+	/* budget: further 6 bits used below, totalling 40 bits */
+
 	/* stop bit - end of Repeated E-UTRAN Neighbour Cells sequence: */
 	bitvec_set_bit(bv, 0);