diff --git a/src/server/gdb_server.c b/src/server/gdb_server.c
index cf7a2bde0..f59eb5029 100644
--- a/src/server/gdb_server.c
+++ b/src/server/gdb_server.c
@@ -3753,18 +3753,30 @@ static int gdb_input_inner(struct connection *connection)
 					break;
 
 				case 'j':
-					/* DEPRECATED */
-					/* packet supported only by smp target i.e cortex_a.c*/
-					/* handle smp packet replying coreid played to gbd */
-					gdb_read_smp_packet(connection, packet, packet_size);
+					if (strncmp(packet, "jc", 2) == 0) {
+						/* DEPRECATED */
+						/* packet supported only by smp target i.e cortex_a.c*/
+						/* handle smp packet replying coreid played to gbd */
+						gdb_read_smp_packet(connection, packet, packet_size);
+					} else {
+						/* ignore unknown packets */
+						LOG_DEBUG("ignoring 0x%2.2x packet", packet[0]);
+						retval = gdb_put_packet(connection, "", 0);
+					}
 					break;
 
 				case 'J':
-					/* DEPRECATED */
-					/* packet supported only by smp target i.e cortex_a.c */
-					/* handle smp packet setting coreid to be played at next
-					 * resume to gdb */
-					gdb_write_smp_packet(connection, packet, packet_size);
+					if (strncmp(packet, "jc", 2) == 0) {
+						/* DEPRECATED */
+						/* packet supported only by smp target i.e cortex_a.c */
+						/* handle smp packet setting coreid to be played at next
+						* resume to gdb */
+						gdb_read_smp_packet(connection, packet, packet_size);
+					} else {
+						/* ignore unknown packets */
+						LOG_DEBUG("ignoring 0x%2.2x packet", packet[0]);
+						retval = gdb_put_packet(connection, "", 0);
+					}
 					break;
 
 				case 'F':
diff --git a/src/target/smp.c b/src/target/smp.c
index 41ca880d4..8a9dd2d9d 100644
--- a/src/target/smp.c
+++ b/src/target/smp.c
@@ -54,16 +54,13 @@ int gdb_read_smp_packet(struct connection *connection,
 	LOG_WARNING(DEPRECATED_MSG);
 
 	if (target->smp) {
-		if (strncmp(packet, "jc", 2) == 0) {
-			const uint32_t len = sizeof(target->gdb_service->core[0]);
-			char hex_buffer[len * 2 + 1];
-			uint8_t buffer[len];
-			buf_set_u32(buffer, 0, len * 8, target->gdb_service->core[0]);
-			size_t pkt_len = hexify(hex_buffer, buffer, sizeof(buffer),
-				sizeof(hex_buffer));
-
-			retval = gdb_put_packet(connection, hex_buffer, pkt_len);
-		}
+		const uint32_t len = sizeof(target->gdb_service->core[0]);
+		char hex_buffer[len * 2 + 1];
+		uint8_t buffer[len];
+		buf_set_u32(buffer, 0, len * 8, target->gdb_service->core[0]);
+		size_t pkt_len = hexify(hex_buffer, buffer, sizeof(buffer),
+			sizeof(hex_buffer));
+		retval = gdb_put_packet(connection, hex_buffer, pkt_len);
 	} else
 		retval = gdb_put_packet(connection, "E01", 3);
 	return retval;