diff --git a/src/encoding.cpp b/src/encoding.cpp
index 55838fb5..b460d41c 100644
--- a/src/encoding.cpp
+++ b/src/encoding.cpp
@@ -263,7 +263,7 @@ static int write_ia_rest_uplink_sba(bitvec *dest, uint32_t fn, uint8_t alpha, ui
 }
 
 static int write_ia_rest_uplink_mba(const gprs_rlcmac_ul_tbf *tbf, bitvec *dest, uint8_t usf,
-				    uint8_t alpha, uint8_t gamma)
+				    uint8_t alpha, uint8_t gamma, int8_t ta_idx)
 {
 	int rc = 0;
 
@@ -282,8 +282,8 @@ static int write_ia_rest_uplink_mba(const gprs_rlcmac_ul_tbf *tbf, bitvec *dest,
 	rc = write_alpha_gamma(dest, alpha, gamma);
 	CHECK(rc);
 
-	/* No TIMING_ADVANCE_INDEX */
-	SET_0(dest);
+	rc = write_ta_index(dest, ta_idx);
+	CHECK(rc);
 
 	/* No TBF_STARTING_TIME */
 	SET_0(dest);
@@ -311,7 +311,7 @@ static int write_ia_rest_egprs_uplink_mba(bitvec * dest, uint32_t fn, uint8_t al
 }
 
 static int write_ia_rest_egprs_uplink_sba(const gprs_rlcmac_ul_tbf *tbf, bitvec * dest, uint8_t usf,
-					  uint8_t alpha, uint8_t gamma)
+					  uint8_t alpha, uint8_t gamma, int8_t ta_idx)
 {
 	int rc = 0;
 
@@ -339,8 +339,8 @@ static int write_ia_rest_egprs_uplink_sba(const gprs_rlcmac_ul_tbf *tbf, bitvec
 	rc = write_alpha_gamma(dest, alpha, gamma);
 	CHECK(rc);
 
-	/* No TIMING_ADVANCE_INDEX */
-	SET_0(dest);
+	rc = write_ta_index(dest, ta_idx);
+	CHECK(rc);
 
 	/* No TBF_STARTING_TIME */
 	SET_0(dest);
@@ -514,7 +514,7 @@ int Encoding::write_immediate_assignment(
 
 		if (as_ul_tbf(tbf) != NULL) {
 			dest->cur_bit = wp;
-			rc = write_ia_rest_egprs_uplink_sba(as_ul_tbf(tbf), dest, usf, alpha, gamma);
+			rc = write_ia_rest_egprs_uplink_sba(as_ul_tbf(tbf), dest, usf, alpha, gamma, ta_idx);
 		} else {
 			dest->cur_bit = wp;
 			rc = write_ia_rest_egprs_uplink_mba(dest, fn, alpha, gamma);
@@ -527,7 +527,7 @@ int Encoding::write_immediate_assignment(
 
 		if (as_ul_tbf(tbf) != NULL) {
 			dest->cur_bit = wp;
-			rc = write_ia_rest_uplink_mba(as_ul_tbf(tbf), dest, usf, alpha, gamma);
+			rc = write_ia_rest_uplink_mba(as_ul_tbf(tbf), dest, usf, alpha, gamma, ta_idx);
 		} else {
 			dest->cur_bit = wp;
 			rc = write_ia_rest_uplink_sba(dest, fn, alpha, gamma);
diff --git a/tests/types/TypesTest.cpp b/tests/types/TypesTest.cpp
index 822bd514..589f1562 100644
--- a/tests/types/TypesTest.cpp
+++ b/tests/types/TypesTest.cpp
@@ -497,7 +497,7 @@ void test_immediate_assign_ul0m()
 				 0x23, /* TA */
 				 0x00, /* 0-length §10.5.2.21 Mobile Allocation */
 				 /* ETSI TS 44.018 §10.5.2.16 IA Rest Octets */
-				 0xc8, 0x02, 0x1b, 0xa0, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b, };
+				 0xc8, 0x02, 0x1b, 0xa2, 0x0b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b, };
 
 	check_imm_ass(tbf, false, GSM_L1_BURST_TYPE_ACCESS_0, res, sizeof(res), "ia_rest_uplink(MBA)");
 }
@@ -537,7 +537,7 @@ void test_immediate_assign_ul1s()
 				 0x23, /* TA */
 				 0x00, /* 0-length §10.5.2.21 Mobile Allocation */
 				 /* ETSI TS 44.018 §10.5.2.16 IA Rest Octets */
-				 0x46, 0xa0, 0x08, 0x00, 0x17, 0x40, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b, };
+				 0x46, 0xa0, 0x08, 0x00, 0x17, 0x44, 0x0b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b, };
 
 	check_imm_ass(tbf, false, GSM_L1_BURST_TYPE_ACCESS_1, res, sizeof(res), "ia_rest_egprs_uplink(SBA)");
 }
diff --git a/tests/types/TypesTest.ok b/tests/types/TypesTest.ok
index c6974d5a..a5c58b89 100644
--- a/tests/types/TypesTest.ok
+++ b/tests/types/TypesTest.ok
@@ -9,13 +9,13 @@ show_rbb: IIRRIIIR
 [11] DL Immediate Assignment <ia_rest_downlink>:
 	06 3f 30 0d 23 6d 7f 03 18 23 00 d0 00 00 00 08 17 47 08 0b 5b 2b 2b 
 [11] UL Immediate Assignment <ia_rest_uplink(MBA)>:
-	06 3f 10 0d 23 6d 0d 03 18 23 00 c8 02 1b a0 2b 2b 2b 2b 2b 2b 2b 2b 
+	06 3f 10 0d 23 6d 0d 03 18 23 00 c8 02 1b a2 0b 2b 2b 2b 2b 2b 2b 2b 
 [11] UL Immediate Assignment <ia_rest_uplink(SBA)>:
 	06 3f 10 0d 23 6d 0d 03 18 23 00 c5 d0 80 b5 ab 2b 2b 2b 2b 2b 2b 2b 
 [11] UL Immediate Assignment <ia_rest_egprs_uplink(MBA)>:
 	06 3f 10 0d 23 6d 7f 03 18 23 00 46 97 40 0b 58 2b 2b 2b 2b 2b 2b 2b 
 [11] UL Immediate Assignment <ia_rest_egprs_uplink(SBA)>:
-	06 3f 10 0d 23 6d 7f 03 18 23 00 46 a0 08 00 17 40 2b 2b 2b 2b 2b 2b 
+	06 3f 10 0d 23 6d 7f 03 18 23 00 46 a0 08 00 17 44 0b 2b 2b 2b 2b 2b 
 assignment reject: 06 3a 10 7f 06 36 14 7f 06 36 14 7f 06 36 14 7f 06 36 14 c0 2b 2b 
 assignment reject: 06 3a 10 70 06 36 14 70 06 36 14 70 06 36 14 70 06 36 14 0b 2b 2b 
 Testing LBS utility...