diff --git a/include/osmocom/sgsn/gprs_sndcp_comp.h b/include/osmocom/sgsn/gprs_sndcp_comp.h
index c04f7d4..e01a9d7 100644
--- a/include/osmocom/sgsn/gprs_sndcp_comp.h
+++ b/include/osmocom/sgsn/gprs_sndcp_comp.h
@@ -41,9 +41,9 @@
 	uint8_t comp[MAX_COMP];	/* see also: 6.5.1.1.5 and 6.6.1.1.5 */
 
 	/* Algorithm parameters */
-	int algo;		/* Algorithm type (see gprs_sndcp_xid.h) */
-	int compclass;		/* See gprs_sndcp_xid.h/c */
-	void *state;		/* Algorithm status and parameters */
+	union gprs_sndcp_comp_algo algo;
+	enum gprs_sndcp_xid_param_types compclass;	/* See gprs_sndcp_xid.h/c */
+	void *state;					/* Algorithm status and parameters */
 };
 
 #define MAX_COMP 16	/* Maximum number of possible pcomp/dcomp values */
diff --git a/include/osmocom/sgsn/gprs_sndcp_xid.h b/include/osmocom/sgsn/gprs_sndcp_xid.h
index e64bc52..0dce43e 100644
--- a/include/osmocom/sgsn/gprs_sndcp_xid.h
+++ b/include/osmocom/sgsn/gprs_sndcp_xid.h
@@ -32,6 +32,24 @@
 #define MAX_NSAPI 11	/* Maximum number usable NSAPIs */
 #define MAX_ROHC 16	/* Maximum number of ROHC compression profiles */
 
+/* According to: 3GPP TS 44.065, 6.5.1.1.4 Algorithm identifier */
+enum gprs_sndcp_hdr_comp_algo {
+	RFC_1144,		/* TCP/IP header compression, see also 6.5.2 */
+	RFC_2507,		/* TCP/UDP/IP header compression, see also: 6.5.3 */
+	ROHC			/* Robust Header Compression, see also 6.5.4 */
+};
+
+/* According to: 3GPP TS 44.065, 6.5.1.1.4 Algorithm identifier */
+enum gprs_sndcp_data_comp_algo {
+	V42BIS,			/* V.42bis data compression, see also 6.6.2 */
+	V44			/* V44 data compression, see also: 6.6.3 */
+};
+
+union gprs_sndcp_comp_algo {
+	enum gprs_sndcp_hdr_comp_algo pcomp;
+	enum gprs_sndcp_data_comp_algo dcomp;
+};
+
 /* According to: 3GPP TS 44.065, 6.5.1.1 Format of the protocol control
  * information compression field (Figure 7) and 3GPP TS 44.065, 
  * 6.6.1.1 Format of the data compression field (Figure 9) */
@@ -45,7 +63,7 @@
 	unsigned int entity;
 
 	/* Algorithm identifier, see also: 6.5.1.1.4 and 6.6.1.1.4 */
-	int algo;
+	union gprs_sndcp_comp_algo algo;
 
 	/* Number of contained PCOMP / DCOMP values */
 	uint8_t comp_len;
@@ -62,24 +80,12 @@
 	struct gprs_sndcp_dcomp_v44_params *v44_params;
 };
 
-/* According to: 3GPP TS 44.065, 6.5.1.1.4 Algorithm identifier */
-enum gprs_sndcp_hdr_comp_algo {
-	RFC_1144,		/* TCP/IP header compression, see also 6.5.2 */
-	RFC_2507,		/* TCP/UDP/IP header compression, see also: 6.5.3 */
-	ROHC			/* Robust Header Compression, see also 6.5.4 */
-};
-
-/* According to: 3GPP TS 44.065, 6.5.1.1.4 Algorithm identifier */
-enum gprs_sndcp_data_comp_algo {
-	V42BIS,			/* V.42bis data compression, see also 6.6.2 */
-	V44			/* V44 data compression, see also: 6.6.3 */
-};
-
 /* According to: 3GPP TS 44.065, 8 SNDCP XID parameters */
 enum gprs_sndcp_xid_param_types {
 	SNDCP_XID_VERSION_NUMBER,
 	SNDCP_XID_DATA_COMPRESSION,	/* See also: subclause 6.6.1 */
 	SNDCP_XID_PROTOCOL_COMPRESSION,	/* See also: subclause 6.5.1 */
+	SNDCP_XID_INVALID_COMPRESSION   /* Not part of the spec; this means we found an invalid value */
 };
 
 /* According to: 3GPP TS 44.065, 6.5.2.1 Parameters (Table 5) */
@@ -209,7 +215,7 @@
 
 /* Find out to which compression class the specified comp-field belongs
  * (header compression or data compression?) */
-int gprs_sndcp_get_compression_class(
+enum gprs_sndcp_xid_param_types gprs_sndcp_get_compression_class(
 				const struct gprs_sndcp_comp_field *comp_field);
 
 /* Dump a list with SNDCP-XID fields (Debug) */
diff --git a/src/gprs/gprs_sndcp.c b/src/gprs/gprs_sndcp.c
index 52eeb75..f0239cb 100644
--- a/src/gprs/gprs_sndcp.c
+++ b/src/gprs/gprs_sndcp.c
@@ -934,7 +934,7 @@
 		rfc1144_params.s01 = sgsn->cfg.pcomp_rfc1144.s01;
 		rfc1144_comp_field.p = 1;
 		rfc1144_comp_field.entity = entity;
-		rfc1144_comp_field.algo = RFC_1144;
+		rfc1144_comp_field.algo.pcomp = RFC_1144;
 		rfc1144_comp_field.comp[RFC1144_PCOMP1] = 1;
 		rfc1144_comp_field.comp[RFC1144_PCOMP2] = 2;
 		rfc1144_comp_field.comp_len = RFC1144_PCOMP_NUM;
@@ -952,7 +952,7 @@
 		v42bis_params.p2 = sgsn->cfg.dcomp_v42bis.p2;
 		v42bis_comp_field.p = 1;
 		v42bis_comp_field.entity = entity;
-		v42bis_comp_field.algo = V42BIS;
+		v42bis_comp_field.algo.dcomp = V42BIS;
 		v42bis_comp_field.comp[V42BIS_DCOMP1] = 1;
 		v42bis_comp_field.comp_len = V42BIS_DCOMP_NUM;
 		v42bis_comp_field.v42bis_params = &v42bis_params;
@@ -1021,7 +1021,7 @@
 	comp_field->p = 0;
 
 	/* Process proposed parameters */
-	switch (comp_field->algo) {
+	switch (comp_field->algo.pcomp) {
 	case RFC_1144:
 		if (sgsn->cfg.pcomp_rfc1144.passive
 		    && comp_field->rfc1144_params->nsapi_len > 0) {
@@ -1068,7 +1068,7 @@
 	comp_field->p = 0;
 
 	/* Process proposed parameters */
-	switch (comp_field->algo) {
+	switch (comp_field->algo.dcomp) {
 	case V42BIS:
 		if (sgsn->cfg.dcomp_v42bis.passive &&
 		    comp_field->v42bis_params->nsapi_len > 0) {
diff --git a/src/gprs/gprs_sndcp_comp.c b/src/gprs/gprs_sndcp_comp.c
index 3e02603..0b4c67c 100644
--- a/src/gprs/gprs_sndcp_comp.c
+++ b/src/gprs/gprs_sndcp_comp.c
@@ -55,32 +55,36 @@
 		memcpy(comp_entity->nsapi,
 		       comp_field->rfc1144_params->nsapi,
 		       sizeof(comp_entity->nsapi));
+		comp_entity->algo.pcomp = comp_field->algo.pcomp;
 	} else if (comp_field->rfc2507_params) {
 		comp_entity->nsapi_len = comp_field->rfc2507_params->nsapi_len;
 		memcpy(comp_entity->nsapi,
 		       comp_field->rfc2507_params->nsapi,
 		       sizeof(comp_entity->nsapi));
+		comp_entity->algo.pcomp = comp_field->algo.pcomp;
 	} else if (comp_field->rohc_params) {
 		comp_entity->nsapi_len = comp_field->rohc_params->nsapi_len;
 		memcpy(comp_entity->nsapi, comp_field->rohc_params->nsapi,
 		       sizeof(comp_entity->nsapi));
+		comp_entity->algo.pcomp = comp_field->algo.pcomp;
 	} else if (comp_field->v42bis_params) {
 		comp_entity->nsapi_len = comp_field->v42bis_params->nsapi_len;
 		memcpy(comp_entity->nsapi,
 		       comp_field->v42bis_params->nsapi,
 		       sizeof(comp_entity->nsapi));
+		comp_entity->algo.dcomp = comp_field->algo.dcomp;
 	} else if (comp_field->v44_params) {
 		comp_entity->nsapi_len = comp_field->v44_params->nsapi_len;
 		memcpy(comp_entity->nsapi,
 		       comp_field->v44_params->nsapi,
 		       sizeof(comp_entity->nsapi));
+		comp_entity->algo.dcomp = comp_field->algo.dcomp;
 	} else {
 		/* The caller is expected to check carefully if the all
 		 * data fields required for compression entity creation
 		 * are present. Otherwise we blow an assertion here */
 		OSMO_ASSERT(false);
 	}
-	comp_entity->algo = comp_field->algo;
 
 	/* Check if an NSAPI is selected, if not, it does not make sense
 	 * to create the compression entity, since the caller should
@@ -93,17 +97,20 @@
 	comp_entity->compclass = gprs_sndcp_get_compression_class(comp_field);
 
 	/* Create an algorithm specific compression context */
-	if (comp_entity->compclass == SNDCP_XID_PROTOCOL_COMPRESSION) {
+	switch (comp_entity->compclass) {
+	case SNDCP_XID_PROTOCOL_COMPRESSION:
 		if (gprs_sndcp_pcomp_init(ctx, comp_entity, comp_field) != 0) {
 			talloc_free(comp_entity);
 			comp_entity = NULL;
 		}
-	} else if (comp_entity->compclass == SNDCP_XID_DATA_COMPRESSION) {
+		break;
+	case SNDCP_XID_DATA_COMPRESSION:
 		if (gprs_sndcp_dcomp_init(ctx, comp_entity, comp_field) != 0) {
 			talloc_free(comp_entity);
 			comp_entity = NULL;
 		}
-	} else {
+		break;
+	default:
 		/* comp_field is somehow invalid */
 		OSMO_ASSERT(false);
 	}
diff --git a/src/gprs/gprs_sndcp_dcomp.c b/src/gprs/gprs_sndcp_dcomp.c
index 04ff491..00e40a7 100644
--- a/src/gprs/gprs_sndcp_dcomp.c
+++ b/src/gprs/gprs_sndcp_dcomp.c
@@ -83,7 +83,7 @@
 	OSMO_ASSERT(comp_field);
 
 	if (comp_entity->compclass == SNDCP_XID_DATA_COMPRESSION
-	    && comp_entity->algo == V42BIS) {
+	    && comp_entity->algo.dcomp == V42BIS) {
 		OSMO_ASSERT(comp_field->v42bis_params);
 		comp_entity->state =
 		    v42bis_init(ctx, NULL, comp_field->v42bis_params->p0,
@@ -114,7 +114,7 @@
 	OSMO_ASSERT(comp_entity);
 
 	if (comp_entity->compclass == SNDCP_XID_DATA_COMPRESSION
-	    && comp_entity->algo == V42BIS) {
+	    && comp_entity->algo.dcomp == V42BIS) {
 		if (comp_entity->state) {
 			v42bis_free((v42bis_state_t *) comp_entity->state);
 			comp_entity->state = NULL;
@@ -293,7 +293,7 @@
 
 	/* Note: Currently V42BIS is the only compression method we
 	 * support, so the only allowed algorithm is V42BIS */
-	OSMO_ASSERT(comp_entity->algo == V42BIS);
+	OSMO_ASSERT(comp_entity->algo.dcomp == V42BIS);
 
 	/* Find pcomp_index */
 	pcomp_index = gprs_sndcp_comp_get_idx(comp_entity, pcomp);
@@ -339,7 +339,7 @@
 
 	/* Note: Currently V42BIS is the only compression method we
 	 * support, so the only allowed algorithm is V42BIS */
-	OSMO_ASSERT(comp_entity->algo == V42BIS);
+	OSMO_ASSERT(comp_entity->algo.dcomp == V42BIS);
 
 	/* Run compression algo */
 	rc = v42bis_compress_unitdata(&pcomp_index, data, len,
diff --git a/src/gprs/gprs_sndcp_pcomp.c b/src/gprs/gprs_sndcp_pcomp.c
index 2911b5e..5f7f22a 100644
--- a/src/gprs/gprs_sndcp_pcomp.c
+++ b/src/gprs/gprs_sndcp_pcomp.c
@@ -53,7 +53,7 @@
 	OSMO_ASSERT(comp_field);
 
 	if (comp_entity->compclass == SNDCP_XID_PROTOCOL_COMPRESSION
-	    && comp_entity->algo == RFC_1144) {
+	    && comp_entity->algo.pcomp == RFC_1144) {
 		OSMO_ASSERT(comp_field->rfc1144_params);
 		comp_entity->state =
 		    slhc_init(ctx, comp_field->rfc1144_params->s01 + 1,
@@ -79,7 +79,7 @@
 	OSMO_ASSERT(comp_entity);
 
 	if (comp_entity->compclass == SNDCP_XID_PROTOCOL_COMPRESSION
-	    && comp_entity->algo == RFC_1144) {
+	    && comp_entity->algo.pcomp == RFC_1144) {
 		if (comp_entity->state) {
 			slhc_free((struct slcompress *)comp_entity->state);
 			comp_entity->state = NULL;
@@ -214,7 +214,7 @@
 
 	/* Note: Currently RFC1144 is the only compression method we
 	 * support, so the only allowed algorithm is RFC1144 */
-	OSMO_ASSERT(comp_entity->algo == RFC_1144);
+	OSMO_ASSERT(comp_entity->algo.pcomp == RFC_1144);
 
 	/* Find pcomp_index */
 	pcomp_index = gprs_sndcp_comp_get_idx(comp_entity, pcomp);
@@ -263,7 +263,7 @@
 
 	/* Note: Currently RFC1144 is the only compression method we
 	 * support, so the only allowed algorithm is RFC1144 */
-	OSMO_ASSERT(comp_entity->algo == RFC_1144);
+	OSMO_ASSERT(comp_entity->algo.pcomp == RFC_1144);
 
 	/* Run compression algo */
 	rc = rfc1144_compress(&pcomp_index, data, len, comp_entity->state);
diff --git a/src/gprs/gprs_sndcp_xid.c b/src/gprs/gprs_sndcp_xid.c
index 09e21f5..a19f645 100644
--- a/src/gprs/gprs_sndcp_xid.c
+++ b/src/gprs/gprs_sndcp_xid.c
@@ -42,9 +42,8 @@
  * about the referenced algorithm to the parser. */
 struct entity_algo_table {
 	unsigned int entity;	/* see also: 6.5.1.1.3 and 6.6.1.1.3 */
-	unsigned int algo;	/* see also: 6.5.1.1.4 and 6.6.1.1.4 */
-	unsigned int compclass;	/* Can be either SNDCP_XID_DATA_COMPRESSION or
-				   SNDCP_XID_PROTOCOL_COMPRESSION */
+	union gprs_sndcp_comp_algo algo;
+	enum gprs_sndcp_xid_param_types compclass;
 };
 
 /* FUNCTIONS RELATED TO SNDCP-XID ENCODING */
@@ -386,6 +385,7 @@
 	int len;
 	int expected_length;
 	int i;
+	enum gprs_sndcp_xid_param_types compclass;
 
 	uint8_t payload_bytes[256];
 	int payload_bytes_len = -1;
@@ -443,7 +443,17 @@
 	OSMO_ASSERT(comp_field->entity <= 0x1f);
 
 	/* Check if the algorithm number is within bounds */
-	OSMO_ASSERT(comp_field->algo >= 0 && comp_field->algo <= 0x1f);
+	compclass = gprs_sndcp_get_compression_class(comp_field);
+	switch (compclass) {
+	case SNDCP_XID_PROTOCOL_COMPRESSION:
+		OSMO_ASSERT(comp_field->algo.pcomp >= 0 && comp_field->algo.pcomp <= 0x1f);
+		break;
+	case SNDCP_XID_DATA_COMPRESSION:
+		OSMO_ASSERT(comp_field->algo.dcomp >= 0 && comp_field->algo.dcomp <= 0x1f);
+		break;
+	default:
+		OSMO_ASSERT(false);
+	}
 
 	/* Zero out buffer */
 	memset(dst, 0, dst_maxlen);
@@ -459,7 +469,10 @@
 
 	/* Encode algorithm number */
 	if (comp_field->p) {
-		*dst |= comp_field->algo & 0x1F;
+		if (compclass == SNDCP_XID_PROTOCOL_COMPRESSION)
+			*dst |= comp_field->algo.pcomp & 0x1F;
+		else
+			*dst |= comp_field->algo.dcomp & 0x1F;
 		dst++;
 		dst_counter++;
 	}
@@ -501,7 +514,7 @@
 
 /* Find out to which compression class the specified comp-field belongs
  * (header compression or data compression?) */
-int gprs_sndcp_get_compression_class(const struct gprs_sndcp_comp_field
+enum gprs_sndcp_xid_param_types gprs_sndcp_get_compression_class(const struct gprs_sndcp_comp_field
 				     *comp_field)
 {
 	OSMO_ASSERT(comp_field);
@@ -517,7 +530,7 @@
 	else if (comp_field->v44_params)
 		return SNDCP_XID_DATA_COMPRESSION;
 	else
-		return -EINVAL;
+		return SNDCP_XID_INVALID_COMPRESSION;
 }
 
 /* Convert all compression fields to bytstreams */
@@ -1005,10 +1018,10 @@
 	return byte_counter;
 }
 
-/* Lookup algorithm identfier by entity ID */
-static int lookup_algorithm_identifier(int entity, const struct
-				       entity_algo_table
-				       *lt, unsigned int lt_len, int compclass)
+/* Lookup protocol compression algorithm identfier by entity ID */
+static enum gprs_sndcp_hdr_comp_algo lookup_algorithm_identifier_pcomp(int entity,
+				       const struct entity_algo_table *lt,
+				       unsigned int lt_len)
 {
 	int i;
 
@@ -1017,26 +1030,46 @@
 
 	for (i = 0; i < lt_len; i++) {
 		if ((lt[i].entity == entity)
-		    && (lt[i].compclass == compclass))
-			return lt[i].algo;
+		    && (lt[i].compclass == SNDCP_XID_PROTOCOL_COMPRESSION))
+			return lt[i].algo.pcomp;
 	}
 
-	return -1;
+	return SNDCP_XID_INVALID_COMPRESSION;
+}
+
+/* Lookup a data compression algorithm identfier by entity ID */
+static enum gprs_sndcp_data_comp_algo lookup_algorithm_identifier_dcomp(int entity,
+				       const struct entity_algo_table *lt,
+				       unsigned int lt_len)
+{
+	int i;
+
+	if (!lt)
+		return -1;
+
+	for (i = 0; i < lt_len; i++) {
+		if ((lt[i].entity == entity)
+		    && (lt[i].compclass == SNDCP_XID_DATA_COMPRESSION))
+			return lt[i].algo.dcomp;
+	}
+
+	return SNDCP_XID_INVALID_COMPRESSION;
 }
 
 /* Helper function for decode_comp_field(), decodes
  * numeric pcomp/dcomp values */
 static int decode_comp_values(struct gprs_sndcp_comp_field *comp_field,
-			      const uint8_t *src, int compclass)
+			      const uint8_t *src, enum gprs_sndcp_xid_param_types compclass)
 {
 	int src_counter = 0;
 	int i;
 
 	if (comp_field->p) {
 		/* Determine the number of expected PCOMP/DCOMP values */
-		if (compclass == SNDCP_XID_PROTOCOL_COMPRESSION) {
+		switch (compclass) {
+		case SNDCP_XID_PROTOCOL_COMPRESSION:
 			/* For protocol compression */
-			switch (comp_field->algo) {
+			switch (comp_field->algo.pcomp) {
 			case RFC_1144:
 				comp_field->comp_len = RFC1144_PCOMP_NUM;
 				break;
@@ -1052,9 +1085,10 @@
 			default:
 				return -EINVAL;
 			}
-		} else {
+			break;
+		case SNDCP_XID_DATA_COMPRESSION:
 			/* For data compression */
-			switch (comp_field->algo) {
+			switch (comp_field->algo.dcomp) {
 			case V42BIS:
 				comp_field->comp_len = V42BIS_DCOMP_NUM;
 				break;
@@ -1067,6 +1101,9 @@
 			default:
 				return -EINVAL;
 			}
+			break;
+		default:
+			return -EINVAL;
 		}
 
 		for (i = 0; i < comp_field->comp_len; i++) {
@@ -1094,7 +1131,7 @@
 {
 	int rc;
 
-	switch (comp_field->algo) {
+	switch (comp_field->algo.pcomp) {
 	case RFC_1144:
 		comp_field->rfc1144_params = talloc_zero(comp_field, struct
 					gprs_sndcp_pcomp_rfc1144_params);
@@ -1142,7 +1179,7 @@
 {
 	int rc;
 
-	switch (comp_field->algo) {
+	switch (comp_field->algo.dcomp) {
 	case V42BIS:
 		comp_field->v42bis_params = talloc_zero(comp_field, struct
 					gprs_sndcp_dcomp_v42bis_params);
@@ -1180,7 +1217,8 @@
 static int decode_comp_field(struct gprs_sndcp_comp_field *comp_field,
 			     const uint8_t *src, unsigned int src_len,
 			     const struct entity_algo_table *lt,
-			     unsigned int lt_len, int compclass)
+			     unsigned int lt_len,
+			     enum gprs_sndcp_xid_param_types compclass)
 {
 	int src_counter = 0;
 	unsigned int len;
@@ -1205,15 +1243,34 @@
 
 	/* Decode algorithm number (if present) */
 	if (comp_field->p) {
-		comp_field->algo = (*src) & 0x1F;
+		switch (compclass) {
+		case SNDCP_XID_PROTOCOL_COMPRESSION:
+			comp_field->algo.pcomp = (*src) & 0x1F;
+			break;
+		case SNDCP_XID_DATA_COMPRESSION:
+			comp_field->algo.dcomp = (*src) & 0x1F;
+			break;
+		default:
+			return -EINVAL;
+		}
 		src_counter++;
 		src++;
 	}
 	/* Alternatively take the information from the lookup table */
-	else
-		comp_field->algo =
-		    lookup_algorithm_identifier(comp_field->entity, lt,
-						lt_len, compclass);
+	else {
+		switch (compclass) {
+		case SNDCP_XID_PROTOCOL_COMPRESSION:
+			comp_field->algo.pcomp =
+			    lookup_algorithm_identifier_pcomp(comp_field->entity, lt, lt_len);
+			break;
+		case SNDCP_XID_DATA_COMPRESSION:
+			comp_field->algo.dcomp =
+			    lookup_algorithm_identifier_dcomp(comp_field->entity, lt, lt_len);
+			break;
+		default:
+			return -EINVAL;
+		}
+	}
 
 	/* Decode length field */
 	len = *src;
@@ -1368,7 +1425,7 @@
 {
 	struct gprs_sndcp_comp_field *comp_field;
 	int i = 0;
-	int rc;
+	enum gprs_sndcp_xid_param_types compclass;
 
 	if (!comp_fields)
 		return -EINVAL;
@@ -1378,19 +1435,23 @@
 	memset(lt, 0, sizeof(*lt));
 
 	llist_for_each_entry(comp_field, comp_fields, list) {
-		if (comp_field->algo >= 0) {
-			lt[i].entity = comp_field->entity;
-			lt[i].algo = comp_field->algo;
-			rc = gprs_sndcp_get_compression_class(comp_field);
-
-			if (rc < 0) {
-				memset(lt, 0, sizeof(*lt));
-				return -EINVAL;
-			}
-
-			lt[i].compclass = rc;
-			i++;
+		compclass = gprs_sndcp_get_compression_class(comp_field);
+		switch (compclass) {
+		case SNDCP_XID_PROTOCOL_COMPRESSION:
+			lt[i].algo.pcomp = comp_field->algo.pcomp;
+			break;
+		case SNDCP_XID_DATA_COMPRESSION:
+			lt[i].algo.dcomp = comp_field->algo.dcomp;
+			break;
+		case SNDCP_XID_INVALID_COMPRESSION:
+			continue;
+		default:
+			memset(lt, 0, sizeof(*lt));
+			return -EINVAL;
 		}
+		lt[i].compclass = compclass;
+		lt[i].entity = comp_field->entity;
+		i++;
 	}
 
 	return i;
@@ -1402,7 +1463,10 @@
 				      *comp_field_dst, const struct
 				      gprs_sndcp_comp_field *comp_field_src)
 {
-	if (comp_field_dst->algo < 0)
+	enum gprs_sndcp_xid_param_types compclass;
+
+	compclass = gprs_sndcp_get_compression_class(comp_field_dst);
+	if (compclass == SNDCP_XID_INVALID_COMPRESSION)
 		return -EINVAL;
 
 	if (comp_field_dst->rfc1144_params && comp_field_src->rfc1144_params) {
@@ -1626,7 +1690,7 @@
 {
 	int i;
 
-	switch (comp_field->algo) {
+	switch (comp_field->algo.pcomp) {
 	case RFC_1144:
 		if (comp_field->rfc1144_params == NULL) {
 			LOGP(DSNDCP, logl,
@@ -1726,7 +1790,7 @@
 {
 	int i;
 
-	switch (comp_field->algo) {
+	switch (comp_field->algo.dcomp) {
 	case V42BIS:
 		if (comp_field->v42bis_params == NULL) {
 			LOGP(DSNDCP, logl,
@@ -1791,15 +1855,26 @@
 {
 	struct gprs_sndcp_comp_field *comp_field;
 	int i;
-	int compclass;
+	enum gprs_sndcp_xid_param_types compclass;
 
 	OSMO_ASSERT(comp_fields);
 
 	llist_for_each_entry(comp_field, comp_fields, list) {
+		compclass = gprs_sndcp_get_compression_class(comp_field);
 		LOGP(DSNDCP, logl, "SNDCP-XID:\n");
 		LOGP(DSNDCP, logl, "struct gprs_sndcp_comp_field {\n");
 		LOGP(DSNDCP, logl, "   entity=%d;\n", comp_field->entity);
-		LOGP(DSNDCP, logl, "   algo=%d;\n", comp_field->algo);
+		switch (compclass) {
+		case SNDCP_XID_PROTOCOL_COMPRESSION:
+			LOGP(DSNDCP, logl, "   algo=%d;\n", comp_field->algo.pcomp);
+			break;
+		case SNDCP_XID_DATA_COMPRESSION:
+			LOGP(DSNDCP, logl, "   algo=%d;\n", comp_field->algo.dcomp);
+			break;
+		default:
+			LOGP(DSNDCP, logl, "   algo invalid!\n");
+			break;
+		}
 		LOGP(DSNDCP, logl, "   comp_len=%d;\n", comp_field->comp_len);
 		if (comp_field->comp_len == 0)
 			LOGP(DSNDCP, logl, "   comp[] = NULL;\n");
@@ -1808,12 +1883,16 @@
 			     comp_field->comp[i]);
 		}
 
-		compclass = gprs_sndcp_get_compression_class(comp_field);
-
-		if (compclass == SNDCP_XID_PROTOCOL_COMPRESSION) {
+		switch (compclass) {
+		case SNDCP_XID_PROTOCOL_COMPRESSION:
 			dump_pcomp_params(comp_field, logl);
-		} else if (compclass == SNDCP_XID_DATA_COMPRESSION) {
+			break;
+		case SNDCP_XID_DATA_COMPRESSION:
 			dump_dcomp_params(comp_field, logl);
+			break;
+		default:
+			LOGP(DSNDCP, logl, "   compression algorithm invalid!\n");
+			break;
 		}
 
 		LOGP(DSNDCP, logl, "}\n");
diff --git a/tests/sndcp_xid/sndcp_xid_test.c b/tests/sndcp_xid/sndcp_xid_test.c
index 5ed695c..56b97e3 100644
--- a/tests/sndcp_xid/sndcp_xid_test.c
+++ b/tests/sndcp_xid/sndcp_xid_test.c
@@ -106,7 +106,7 @@
 	/* Setup rfc1144 compression field */
 	rfc1144_comp_field.p = 1;
 	rfc1144_comp_field.entity = 0;
-	rfc1144_comp_field.algo = RFC_1144;
+	rfc1144_comp_field.algo.pcomp = RFC_1144;
 	rfc1144_comp_field.comp[RFC1144_PCOMP1] = 1;
 	rfc1144_comp_field.comp[RFC1144_PCOMP2] = 2;
 	rfc1144_comp_field.comp_len = RFC1144_PCOMP_NUM;
@@ -126,7 +126,7 @@
 	/* Setup rfc2507 compression field */
 	rfc2507_comp_field.p = 1;
 	rfc2507_comp_field.entity = 1;
-	rfc2507_comp_field.algo = RFC_2507;
+	rfc2507_comp_field.algo.pcomp = RFC_2507;
 	rfc2507_comp_field.comp[RFC2507_PCOMP1] = 3;
 	rfc2507_comp_field.comp[RFC2507_PCOMP2] = 4;
 	rfc2507_comp_field.comp[RFC2507_PCOMP3] = 5;
@@ -173,7 +173,7 @@
 	/* Setup ROHC compression field */
 	rohc_comp_field.p = 1;
 	rohc_comp_field.entity = 2;
-	rohc_comp_field.algo = ROHC;
+	rohc_comp_field.algo.pcomp = ROHC;
 	rohc_comp_field.comp[ROHC_PCOMP1] = 8;
 	rohc_comp_field.comp[ROHC_PCOMP2] = 9;
 	rohc_comp_field.comp_len = ROHC_PCOMP_NUM;
@@ -191,7 +191,7 @@
 	/* Setup v42bis compression field */
 	v42bis_comp_field.p = 1;
 	v42bis_comp_field.entity = 3;
-	v42bis_comp_field.algo = V42BIS;
+	v42bis_comp_field.algo.dcomp = V42BIS;
 	v42bis_comp_field.comp[V42BIS_DCOMP1] = 10;
 	v42bis_comp_field.comp_len = V42BIS_DCOMP_NUM;
 	v42bis_comp_field.v42bis_params = &v42bis_params;
@@ -211,7 +211,7 @@
 	/* Setup v44 compression field */
 	v44_comp_field.p = 1;
 	v44_comp_field.entity = 3;
-	v44_comp_field.algo = V44;
+	v44_comp_field.algo.dcomp = V44;
 	v44_comp_field.comp[V44_DCOMP1] = 10;
 	v44_comp_field.comp[V44_DCOMP2] = 11;
 	v44_comp_field.comp_len = V44_DCOMP_NUM;