diff --git a/src/coding_scheme.c b/src/coding_scheme.c
index 4a5d0d4d..a4ae8827 100644
--- a/src/coding_scheme.c
+++ b/src/coding_scheme.c
@@ -64,6 +64,19 @@ bool mcs_is_edge_gmsk(enum CodingScheme cs)
 	return false;
 }
 
+/* Return 3GPP TS 44.060 §12.10d (EDGE) or Table 11.2.28.2 (GPRS) Channel Coding Command value */
+uint8_t mcs_chan_code(enum CodingScheme cs)
+{
+	if (mcs_is_gprs(cs))
+		return cs - CS1;
+
+	if (mcs_is_edge(cs))
+		return cs - MCS1;
+
+	/* Defaults to (M)CS1 */
+	return 0;
+}
+
 static struct {
 	struct {
 		uint8_t data_header_bits;
diff --git a/src/coding_scheme.h b/src/coding_scheme.h
index 3a9ef250..aac4bba1 100644
--- a/src/coding_scheme.h
+++ b/src/coding_scheme.h
@@ -37,6 +37,8 @@ bool mcs_is_gprs(enum CodingScheme cs);
 bool mcs_is_edge(enum CodingScheme cs);
 bool mcs_is_edge_gmsk(enum CodingScheme cs);
 
+uint8_t mcs_chan_code(enum CodingScheme cs);
+
 enum HeaderType {
 	HEADER_INVALID,
 	HEADER_GPRS_CONTROL,
diff --git a/src/gprs_coding_scheme.cpp b/src/gprs_coding_scheme.cpp
index 8e6593b9..a149f814 100644
--- a/src/gprs_coding_scheme.cpp
+++ b/src/gprs_coding_scheme.cpp
@@ -67,10 +67,7 @@ CodingScheme GprsCodingScheme::get_retx_mcs(const GprsCodingScheme mcs,
 							const GprsCodingScheme demanded_mcs,
 							const unsigned arq_type)
 {
-	OSMO_ASSERT(mcs.to_num() > 0);
-	OSMO_ASSERT(demanded_mcs.to_num() > 0);
-
-	return egprs_mcs_retx_tbl[arq_type][mcs.to_num() - 1][demanded_mcs.to_num() - 1];
+	return egprs_mcs_retx_tbl[arq_type][mcs_chan_code(mcs)][mcs_chan_code(demanded_mcs)];
 }
 
 static struct {
diff --git a/src/gprs_coding_scheme.h b/src/gprs_coding_scheme.h
index 728ffd66..d5604fb4 100644
--- a/src/gprs_coding_scheme.h
+++ b/src/gprs_coding_scheme.h
@@ -82,6 +82,7 @@ private:
 	enum CodingScheme m_scheme;
 };
 
+// FIXME: remove once < comparison operator below is no longer necessary
 inline uint8_t GprsCodingScheme::to_num() const
 {
 	if (mcs_is_gprs(m_scheme))
diff --git a/src/gprs_ms.cpp b/src/gprs_ms.cpp
index f8f6227a..19f2ecb2 100644
--- a/src/gprs_ms.cpp
+++ b/src/gprs_ms.cpp
@@ -523,7 +523,7 @@ void GprsMs::update_error_rate(gprs_rlcmac_tbf *tbf, int error_rate)
 	m_nack_rate_dl = error_rate;
 
 	if (error_rate > bts_data->cs_adj_upper_limit) {
-		if (m_current_cs_dl.to_num() > 1) {
+		if (mcs_chan_code(m_current_cs_dl) > 0) {
 			m_current_cs_dl.dec(mode());
 			LOGP(DRLCMACDL, LOGL_INFO,
 				"MS (IMSI %s): High error rate %d%%, "
@@ -621,7 +621,7 @@ void GprsMs::update_cs_ul(const pcu_l1_meas *meas)
 	int low;
 	int high;
 	GprsCodingScheme new_cs_ul = m_current_cs_ul;
-	uint8_t current_cs_num = m_current_cs_ul.to_num();
+	uint8_t current_cs = mcs_chan_code(m_current_cs_ul);
 
 	bts_data = m_bts->bts_data();
 
@@ -632,8 +632,6 @@ void GprsMs::update_cs_ul(const pcu_l1_meas *meas)
 		return;
 	}
 
-	OSMO_ASSERT(current_cs_num > 0);
-
 	if (!m_current_cs_ul) {
 		LOGP(DRLCMACMEAS, LOGL_ERROR,
 		     "Unable to update UL (M)CS because it's not set: %s\n",
@@ -651,15 +649,15 @@ void GprsMs::update_cs_ul(const pcu_l1_meas *meas)
 	old_link_qual = meas->link_qual;
 
 	if (mcs_is_gprs(m_current_cs_ul)) {
-		if (current_cs_num > MAX_GPRS_CS)
-			current_cs_num = MAX_GPRS_CS;
-		low  = bts_data->cs_lqual_ranges[current_cs_num-1].low;
-		high = bts_data->cs_lqual_ranges[current_cs_num-1].high;
+		if (current_cs >= MAX_GPRS_CS)
+			current_cs = MAX_GPRS_CS - 1;
+		low  = bts_data->cs_lqual_ranges[current_cs].low;
+		high = bts_data->cs_lqual_ranges[current_cs].high;
 	} else if (mcs_is_edge(m_current_cs_ul)) {
-		if (current_cs_num > MAX_EDGE_MCS)
-			current_cs_num = MAX_EDGE_MCS;
-		low  = bts_data->mcs_lqual_ranges[current_cs_num-1].low;
-		high = bts_data->mcs_lqual_ranges[current_cs_num-1].high;
+		if (current_cs >= MAX_EDGE_MCS)
+			current_cs = MAX_EDGE_MCS - 1;
+		low  = bts_data->mcs_lqual_ranges[current_cs].low;
+		high = bts_data->mcs_lqual_ranges[current_cs].high;
 	} else {
 		LOGP(DRLCMACMEAS, LOGL_ERROR,
 		     "Unable to update UL (M)CS because it's neither GPRS nor EDGE: %s\n",
diff --git a/tests/ms/MsTest.cpp b/tests/ms/MsTest.cpp
index 2b0bc0ff..aa600e50 100644
--- a/tests/ms/MsTest.cpp
+++ b/tests/ms/MsTest.cpp
@@ -520,11 +520,11 @@ static void test_ms_cs_selection()
 	dl_tbf->set_ms(ms);
 	OSMO_ASSERT(!ms->is_idle());
 
-	OSMO_ASSERT(ms->current_cs_dl().to_num() == 4);
+	OSMO_ASSERT(mcs_chan_code(ms->current_cs_dl()) == 3);
 
 	bts->cs_downgrade_threshold = 200;
 
-	OSMO_ASSERT(ms->current_cs_dl().to_num() == 3);
+	OSMO_ASSERT(mcs_chan_code(ms->current_cs_dl()) == 2);
 
 	talloc_free(dl_tbf);
 
diff --git a/tests/tbf/TbfTest.cpp b/tests/tbf/TbfTest.cpp
index 993ca10b..6dc802cf 100644
--- a/tests/tbf/TbfTest.cpp
+++ b/tests/tbf/TbfTest.cpp
@@ -2737,12 +2737,12 @@ static void tbf_cleanup(gprs_rlcmac_dl_tbf *dl_tbf)
 
 #define CHECK_UNACKED(tbf, cs, bsn) do {				             \
 		OSMO_ASSERT(tbf->window()->m_v_b.is_unacked(bsn));	             \
-		OSMO_ASSERT(tbf->m_rlc.block(bsn)->cs_current_trans.to_num() == cs); \
+		OSMO_ASSERT(mcs_chan_code(tbf->m_rlc.block(bsn)->cs_current_trans) == cs - 1); \
 	} while(0)
 
 #define CHECK_NACKED(tbf, cs, bsn) do {					             \
 		OSMO_ASSERT(tbf->window()->m_v_b.is_nacked(bsn));	             \
-		OSMO_ASSERT(tbf->m_rlc.block(bsn)->cs_current_trans.to_num() == cs); \
+		OSMO_ASSERT(mcs_chan_code(tbf->m_rlc.block(bsn)->cs_current_trans) == cs - 1); \
 	} while(0)
 
 #define MAKE_ACKED(m, tbf, fn, cs, check_unacked) do {			\