diff --git a/src/gprs_coding_scheme.cpp b/src/gprs_coding_scheme.cpp
index 719cbb28..3094ae6c 100644
--- a/src/gprs_coding_scheme.cpp
+++ b/src/gprs_coding_scheme.cpp
@@ -55,12 +55,12 @@ enum GprsCodingScheme::Scheme GprsCodingScheme::egprs_mcs_retx_tbl[MAX_NUM_ARQ]
 
 static struct {
 	struct {
-		unsigned int bytes;
-		unsigned int ext_bits;
-		unsigned int data_header_bits;
+		uint8_t bytes;
+		uint8_t ext_bits;
+		uint8_t data_header_bits;
 	} uplink, downlink;
-	unsigned int data_bytes;
-	unsigned int optional_padding_bits;
+	uint8_t data_bytes;
+	uint8_t optional_padding_bits;
 	const char *name;
 	GprsCodingScheme::HeaderType data_hdr;
 	GprsCodingScheme::Family family;
@@ -99,10 +99,10 @@ static struct {
 
 static struct {
 	struct {
-		int data_header_bits;
+		uint8_t data_header_bits;
 	} uplink, downlink;
-	unsigned int data_block_header_bits;
-	unsigned int num_blocks;
+	uint8_t data_block_header_bits;
+	uint8_t num_blocks;
 	const char *name;
 } hdr_type_info[GprsCodingScheme::NUM_HEADER_TYPES] = {
 	{{0},       {0},       0, 0, "INVALID"},
@@ -134,12 +134,12 @@ GprsCodingScheme GprsCodingScheme::getBySizeUL(unsigned size)
 	return GprsCodingScheme(UNKNOWN);
 }
 
-unsigned int GprsCodingScheme::sizeUL() const
+uint8_t GprsCodingScheme::sizeUL() const
 {
 	return mcs_info[m_scheme].uplink.bytes + (spareBitsUL() ? 1 : 0);
 }
 
-unsigned int GprsCodingScheme::usedSizeUL() const
+uint8_t GprsCodingScheme::usedSizeUL() const
 {
 	if (mcs_info[m_scheme].data_hdr == HEADER_GPRS_DATA)
 		return mcs_info[m_scheme].uplink.bytes;
@@ -147,22 +147,22 @@ unsigned int GprsCodingScheme::usedSizeUL() const
 		return sizeUL();
 }
 
-unsigned int GprsCodingScheme::maxBytesUL() const
+uint8_t GprsCodingScheme::maxBytesUL() const
 {
 	return mcs_info[m_scheme].uplink.bytes;
 }
 
-unsigned int GprsCodingScheme::spareBitsUL() const
+uint8_t GprsCodingScheme::spareBitsUL() const
 {
 	return mcs_info[m_scheme].uplink.ext_bits;
 }
 
-unsigned int GprsCodingScheme::sizeDL() const
+uint8_t GprsCodingScheme::sizeDL() const
 {
 	return mcs_info[m_scheme].downlink.bytes + (spareBitsDL() ? 1 : 0);
 }
 
-unsigned int GprsCodingScheme::usedSizeDL() const
+uint8_t GprsCodingScheme::usedSizeDL() const
 {
 	if (mcs_info[m_scheme].data_hdr == HEADER_GPRS_DATA)
 		return mcs_info[m_scheme].downlink.bytes;
@@ -170,42 +170,42 @@ unsigned int GprsCodingScheme::usedSizeDL() const
 		return sizeDL();
 }
 
-unsigned int GprsCodingScheme::maxBytesDL() const
+uint8_t GprsCodingScheme::maxBytesDL() const
 {
 	return mcs_info[m_scheme].downlink.bytes;
 }
 
-unsigned int GprsCodingScheme::spareBitsDL() const
+uint8_t GprsCodingScheme::spareBitsDL() const
 {
 	return mcs_info[m_scheme].downlink.ext_bits;
 }
 
-unsigned int GprsCodingScheme::maxDataBlockBytes() const
+uint8_t GprsCodingScheme::maxDataBlockBytes() const
 {
 	return mcs_info[m_scheme].data_bytes;
 }
 
-unsigned int GprsCodingScheme::optionalPaddingBits() const
+uint8_t GprsCodingScheme::optionalPaddingBits() const
 {
 	return mcs_info[m_scheme].optional_padding_bits;
 }
 
-unsigned int GprsCodingScheme::numDataBlocks() const
+uint8_t GprsCodingScheme::numDataBlocks() const
 {
 	return hdr_type_info[headerTypeData()].num_blocks;
 }
 
-unsigned int GprsCodingScheme::numDataHeaderBitsUL() const
+uint8_t GprsCodingScheme::numDataHeaderBitsUL() const
 {
 	return hdr_type_info[headerTypeData()].uplink.data_header_bits;
 }
 
-unsigned int GprsCodingScheme::numDataHeaderBitsDL() const
+uint8_t GprsCodingScheme::numDataHeaderBitsDL() const
 {
 	return hdr_type_info[headerTypeData()].downlink.data_header_bits;
 }
 
-unsigned int GprsCodingScheme::numDataBlockHeaderBits() const
+uint8_t GprsCodingScheme::numDataBlockHeaderBits() const
 {
 	return hdr_type_info[headerTypeData()].data_block_header_bits;
 }
diff --git a/src/gprs_coding_scheme.h b/src/gprs_coding_scheme.h
index dfad240b..76cab0f2 100644
--- a/src/gprs_coding_scheme.h
+++ b/src/gprs_coding_scheme.h
@@ -70,7 +70,7 @@ public:
 
 	operator bool() const {return m_scheme != UNKNOWN;}
 	operator Scheme() const {return m_scheme;}
-	unsigned int to_num() const;
+	uint8_t to_num() const;
 
 	GprsCodingScheme& operator =(Scheme s);
 	bool operator == (Scheme s) const;
@@ -91,20 +91,20 @@ public:
 	void dec();
 	void decToSingleBlock(bool *needStuffing);
 
-	unsigned int sizeUL() const;
-	unsigned int sizeDL() const;
-	unsigned int usedSizeUL() const;
-	unsigned int usedSizeDL() const;
-	unsigned int maxBytesUL() const;
-	unsigned int maxBytesDL() const;
-	unsigned int spareBitsUL() const;
-	unsigned int spareBitsDL() const;
-	unsigned int maxDataBlockBytes() const;
-	unsigned int numDataBlocks() const;
-	unsigned int numDataHeaderBitsUL() const;
-	unsigned int numDataHeaderBitsDL() const;
-	unsigned int numDataBlockHeaderBits() const;
-	unsigned int optionalPaddingBits() const;
+	uint8_t sizeUL() const;
+	uint8_t sizeDL() const;
+	uint8_t usedSizeUL() const;
+	uint8_t usedSizeDL() const;
+	uint8_t maxBytesUL() const;
+	uint8_t maxBytesDL() const;
+	uint8_t spareBitsUL() const;
+	uint8_t spareBitsDL() const;
+	uint8_t maxDataBlockBytes() const;
+	uint8_t numDataBlocks() const;
+	uint8_t numDataHeaderBitsUL() const;
+	uint8_t numDataHeaderBitsDL() const;
+	uint8_t numDataBlockHeaderBits() const;
+	uint8_t optionalPaddingBits() const;
 	const char *name() const;
 	HeaderType headerTypeData() const;
 	HeaderType headerTypeControl() const;
@@ -127,7 +127,7 @@ private:
 	enum Scheme m_scheme;
 };
 
-inline unsigned int GprsCodingScheme::to_num() const
+inline uint8_t GprsCodingScheme::to_num() const
 {
 	if (isGprs())
 		return (m_scheme - CS1) + 1;
diff --git a/src/rlc.cpp b/src/rlc.cpp
index 37e83cda..d7f06090 100644
--- a/src/rlc.cpp
+++ b/src/rlc.cpp
@@ -375,7 +375,7 @@ void gprs_rlc_data_block_info_init(struct gprs_rlc_data_block_info *rdbi,
 
 unsigned int gprs_rlc_mcs_cps(GprsCodingScheme cs,
 	enum egprs_puncturing_values punct,
-	enum egprs_puncturing_values punct2, int with_padding)
+	enum egprs_puncturing_values punct2, bool with_padding)
 {
 	/* validate that punct and punct2 are as expected */
 	switch (GprsCodingScheme::Scheme(cs)) {
diff --git a/src/rlc.h b/src/rlc.h
index b62e3ac5..a7e6cf34 100644
--- a/src/rlc.h
+++ b/src/rlc.h
@@ -163,7 +163,7 @@ struct gprs_rlc_data_info {
 	unsigned int es_p;
 	unsigned int rrbp;
 	unsigned int pr;
-	unsigned int num_data_blocks;
+	uint8_t num_data_blocks; /* this can actually be only 0, 1, 2: enforced in gprs_rlc_data_header_init() */
 	unsigned int with_padding;
 	unsigned int data_offs_bits[2];
 	struct gprs_rlc_data_block_info block_info[2];
@@ -218,7 +218,7 @@ void gprs_rlc_data_info_init_ul(struct gprs_rlc_data_info *rlc,
 void gprs_rlc_data_block_info_init(struct gprs_rlc_data_block_info *rdbi,
 	GprsCodingScheme cs, bool with_padding, const unsigned int spb);
 unsigned int gprs_rlc_mcs_cps(GprsCodingScheme cs, enum egprs_puncturing_values
-	punct, enum egprs_puncturing_values punct2, int with_padding);
+	punct, enum egprs_puncturing_values punct2, bool with_padding);
 void gprs_rlc_mcs_cps_decode(unsigned int cps, GprsCodingScheme cs,
 	int *punct, int *punct2, int *with_padding);
 enum egprs_puncturing_values gprs_get_punct_scheme(enum egprs_puncturing_values
diff --git a/src/tbf_dl.cpp b/src/tbf_dl.cpp
index 58b55dcd..b871bc32 100644
--- a/src/tbf_dl.cpp
+++ b/src/tbf_dl.cpp
@@ -666,7 +666,7 @@ struct msgb *gprs_rlcmac_dl_tbf::create_dl_acked_block(
 	unsigned msg_len;
 	bool need_poll;
 	/* TODO: support MCS-7 - MCS-9, where data_block_idx can be 1 */
-	unsigned int data_block_idx = 0;
+	uint8_t data_block_idx = 0;
 	unsigned int rrbp;
 	uint32_t new_poll_fn;
 	int rc;
@@ -752,8 +752,8 @@ struct msgb *gprs_rlcmac_dl_tbf::create_dl_acked_block(
 
 	LOGP(DRLCMACDL, LOGL_DEBUG, "- Copying %u RLC blocks, %u BSNs\n", rlc.num_data_blocks, num_bsns);
 
-	/* Copy block(s) to RLC message */
-	for (data_block_idx = 0; data_block_idx < rlc.num_data_blocks;
+	/* Copy block(s) to RLC message: the num_data_blocks cannot be more than 2 - see assert above */
+	for (data_block_idx = 0; data_block_idx < OSMO_MIN(rlc.num_data_blocks, 2);
 		data_block_idx++)
 	{
 		int bsn;
@@ -777,7 +777,7 @@ struct msgb *gprs_rlcmac_dl_tbf::create_dl_acked_block(
 			OSMO_ASSERT(m_rlc.block(bsn)->next_ps >= EGPRS_PS_1);
 			OSMO_ASSERT(m_rlc.block(bsn)->next_ps <= EGPRS_PS_3);
 		}
-		OSMO_ASSERT(data_block_idx < 2); /* punct defined above as 2-element array */
+
 		punct[data_block_idx] = m_rlc.block(bsn)->next_ps;
 
 		rdbi = &rlc.block_info[data_block_idx];