diff --git a/metadata_exporter.h b/metadata_exporter.h
index 9f5183e..edc0b8f 100644
--- a/metadata_exporter.h
+++ b/metadata_exporter.h
@@ -45,8 +45,6 @@
 #define MD_INPUT_MAX (__MD_INPUT_MAX - 1)
 #define MD_WRITER_MAX (__MD_WRITER_MAX - 1)
 
-#define META_IFACE_INVALID   0x81
-
 #define META_TYPE_INTERFACE  0x01
 #define META_TYPE_CONNECTION 0x02
 #define META_TYPE_POS        0x04
@@ -55,6 +53,23 @@
 #define META_TYPE_RADIO      0x08
 #define META_TYPE_SYSTEM     0x10
 
+#define DEFAULT_RSSI       -127
+#define DEFAULT_RSRQ          0
+#define DEFAULT_RSRP          0
+#define DEFAULT_LTE_BAND      0
+#define DEFAULT_LTE_FREQ      0
+#define DEFAULT_LTE_PCI      -1
+#define DEFAULT_ENODEBID     -1
+#define DEFAULT_ECIO          0
+#define DEFAULT_RSCP          0
+#define DEFAULT_MCCMNC        0
+#define DEFAULT_LAC          -1
+#define DEFAULT_CID          -1
+#define DEFAULT_LTE_PCI      -1
+#define DEFAULT_MODE         -1
+#define DEFAULT_SUBMODE      -1
+#define DEFAULT_DEVICE_STATE -1
+
 enum iface_event {
     IFACE_EVENT_DEV_STATE=1,
     IFACE_EVENT_MODE_CHANGE,
diff --git a/metadata_input_nl_zmq_common.c b/metadata_input_nl_zmq_common.c
index 566de89..cd59824 100644
--- a/metadata_input_nl_zmq_common.c
+++ b/metadata_input_nl_zmq_common.c
@@ -545,14 +545,16 @@ void init_iface_event(struct md_iface_event *mie)
     mie->md_type = META_TYPE_INTERFACE;
     mie->lac = -1;
     mie->cid = -1;
-    mie->rscp = (int16_t) META_IFACE_INVALID;
-    mie->lte_rsrp = (int16_t) META_IFACE_INVALID;
-    mie->rssi = (int8_t) META_IFACE_INVALID;
-    mie->ecio = (int8_t) META_IFACE_INVALID;
-    mie->lte_rssi = (int8_t) META_IFACE_INVALID;
-    mie->lte_rsrq = (int8_t) META_IFACE_INVALID;
-    mie->lte_pci = 0xFFFF;
-    mie->enodeb_id = -1;
+    mie->rscp = DEFAULT_RSCP;
+    mie->lte_rsrp = DEFAULT_RSRP;
+    mie->rssi = DEFAULT_RSSI;
+    mie->ecio = DEFAULT_ECIO;
+    mie->lte_rssi = DEFAULT_RSSI;
+    mie->lte_rsrq = DEFAULT_RSRQ;
+    mie->lte_pci = DEFAULT_LTE_PCI;
+    mie->enodeb_id = DEFAULT_ENODEBID;
+    mie->device_mode = DEFAULT_MODE;
+    mie->device_submode = DEFAULT_SUBMODE;
 }
 
 void init_conn_event(struct md_conn_event* mce)
diff --git a/metadata_writer_file.c b/metadata_writer_file.c
index ac91538..840c51b 100644
--- a/metadata_writer_file.c
+++ b/metadata_writer_file.c
@@ -119,32 +119,32 @@ static void md_file_handle_iface_event(struct md_writer_file *mwf,
         md_file_add_json_string(obj, "imsi", mie->imsi) ||
         md_file_add_json_string(obj, "imei", mie->imei) ||
         md_file_add_json_string(obj, "isp_name", mie->isp_name) ||
-        md_file_add_json_int(obj, "mode", mie->device_mode) ||
-        md_file_add_json_int(obj, "submode", mie->device_submode) ||
-        md_file_add_json_int(obj, "cid", mie->cid) ||
-        md_file_add_json_int(obj, "enodeb_id", mie->enodeb_id) ||
-        md_file_add_json_int(obj, "lac", mie->lac) ||
-        md_file_add_json_int(obj, "device_state", mie->device_state)) {
+        (mie->device_mode != DEFAULT_MODE && md_file_add_json_int(obj, "mode", mie->device_mode)) ||
+        (mie->device_submode != DEFAULT_SUBMODE &&  md_file_add_json_int(obj, "submode", mie->device_submode)) ||
+        (mie->cid != DEFAULT_CID && md_file_add_json_int(obj, "cid", mie->cid)) ||
+        (mie->enodeb_id != DEFAULT_ENODEBID && md_file_add_json_int(obj, "enodeb_id", mie->enodeb_id)) ||
+        (mie->lac != DEFAULT_LAC && md_file_add_json_int(obj, "lac", mie->lac)) ||
+        (mie->device_state != DEFAULT_DEVICE_STATE && md_file_add_json_int(obj, "device_state", mie->device_state))) {
         META_PRINT_SYSLOG(mwf->parent, LOG_ERR, "md_file_handle_iface_event: Can't create iface values to object!");
         json_object_put(obj);
         return;
     }
 
     if (mie->device_mode != 5) {
-        if (md_file_add_json_int(obj, "rssi", mie->rssi) ||
-            md_file_add_json_int(obj, "rscp", mie->rscp) ||
-            md_file_add_json_int(obj, "ecio", mie->ecio)) {
+        if ((mie->rssi != DEFAULT_RSSI && md_file_add_json_int(obj, "rssi", mie->rssi)) ||
+            (mie->rscp != DEFAULT_RSCP && md_file_add_json_int(obj, "rscp", mie->rscp)) ||
+            (mie->ecio != DEFAULT_ECIO && md_file_add_json_int(obj, "ecio", mie->ecio))) {
             META_PRINT_SYSLOG(mwf->parent, LOG_ERR, "md_file_handle_iface_event: Can't add non-LTE values to object!");
             json_object_put(obj);
             return;
         }
     } else { // LTE
-        if (md_file_add_json_int(obj, "lte_rssi", mie->lte_rssi) ||
-            md_file_add_json_int(obj, "lte_rsrp", mie->lte_rsrp) ||
-            md_file_add_json_int(obj, "lte_rsrq", mie->lte_rsrq) ||
-            md_file_add_json_int(obj, "lte_freq", mie->lte_freq) ||
-            md_file_add_json_int(obj, "lte_pci", mie->lte_pci) ||
-            md_file_add_json_int(obj, "lte_band", mie->lte_band)) {
+        if ((mie->lte_rssi != DEFAULT_RSSI && md_file_add_json_int(obj, "lte_rssi", mie->lte_rssi)) ||
+            (mie->lte_rsrp != DEFAULT_RSRP && md_file_add_json_int(obj, "lte_rsrp", mie->lte_rsrp)) ||
+            (mie->lte_rsrq != DEFAULT_RSRQ && md_file_add_json_int(obj, "lte_rsrq", mie->lte_rsrq)) ||
+            (mie->lte_freq != DEFAULT_LTE_FREQ && md_file_add_json_int(obj, "lte_freq", mie->lte_freq)) ||
+            (mie->lte_pci != DEFAULT_LTE_PCI && md_file_add_json_int(obj, "lte_pci", mie->lte_pci)) ||
+            (mie->lte_band != DEFAULT_LTE_BAND && md_file_add_json_int(obj, "lte_band", mie->lte_band))) {
             META_PRINT_SYSLOG(mwf->parent, LOG_ERR, "md_file_handle_iface_event: Can't add LTE values to object!");
             json_object_put(obj);
             return;
diff --git a/metadata_writer_zeromq.c b/metadata_writer_zeromq.c
index 33bdd03..5c4c2ed 100644
--- a/metadata_writer_zeromq.c
+++ b/metadata_writer_zeromq.c
@@ -408,44 +408,44 @@ static json_object *md_zeromq_writer_create_iface_json(const struct md_writer_ze
         (mie->nw_mccmnc &&
             !md_zeromq_writer_create_json_int64(obj, mwz->keys[MD_ZMQ_KEY_NW_MCCMNC],
                 mie->nw_mccmnc)) ||
-        ((mie->cid > -1 && mie->lac > -1) &&
+        ((mie->cid != DEFAULT_CID && mie->lac != DEFAULT_LAC) &&
             (!md_zeromq_writer_create_json_int(obj, mwz->keys[MD_ZMQ_KEY_LAC],
                                         mie->lac) ||
              !md_zeromq_writer_create_json_int(obj, mwz->keys[MD_ZMQ_KEY_CID],
                  mie->cid))) ||
-        (mie->rscp != (int16_t) META_IFACE_INVALID &&
+        (mie->rscp != DEFAULT_RSCP &&
             !md_zeromq_writer_create_json_int(obj, mwz->keys[MD_ZMQ_KEY_RSCP],
                 mie->rscp)) ||
-        (mie->lte_rsrp != (int16_t) META_IFACE_INVALID &&
+        (mie->lte_rsrp != DEFAULT_RSRP &&
             !md_zeromq_writer_create_json_int(obj, mwz->keys[MD_ZMQ_KEY_LTE_RSRP],
                 mie->lte_rsrp)) ||
-        (mie->lte_freq &&
+        (mie->lte_freq != DEFAULT_LTE_FREQ &&
             !md_zeromq_writer_create_json_int(obj, mwz->keys[MD_ZMQ_KEY_LTE_FREQ],
                 mie->lte_freq)) ||
-        (mie->rssi != (int8_t) META_IFACE_INVALID &&
+        (mie->rssi != DEFAULT_RSSI &&
             !md_zeromq_writer_create_json_int(obj, mwz->keys[MD_ZMQ_KEY_RSSI],
                 mie->rssi)) ||
-        (mie->ecio != (int8_t) META_IFACE_INVALID &&
+        (mie->ecio != DEFAULT_ECIO &&
             !md_zeromq_writer_create_json_int(obj, mwz->keys[MD_ZMQ_KEY_ECIO],
                 mie->ecio)) ||
-        (mie->lte_rssi != (int8_t) META_IFACE_INVALID &&
+        (mie->lte_rssi != DEFAULT_RSSI &&
             !md_zeromq_writer_create_json_int(obj, mwz->keys[MD_ZMQ_KEY_LTE_RSSI],
                 mie->lte_rssi)) ||
-        (mie->lte_rsrq != (int8_t) META_IFACE_INVALID &&
+        (mie->lte_rsrq != DEFAULT_RSRQ &&
             !md_zeromq_writer_create_json_int(obj, mwz->keys[MD_ZMQ_KEY_LTE_RSRQ],
                 mie->lte_rsrq)) ||
-        (mie->device_mode && !md_zeromq_writer_create_json_int(obj,
+        (mie->device_mode != DEFAULT_MODE && !md_zeromq_writer_create_json_int(obj,
                 mwz->keys[MD_ZMQ_KEY_DEVICE_MODE], mie->device_mode)) ||
-        (mie->device_submode && !md_zeromq_writer_create_json_int(obj,
+        (mie->device_submode != DEFAULT_SUBMODE && !md_zeromq_writer_create_json_int(obj,
                 mwz->keys[MD_ZMQ_KEY_DEVICE_SUBMODE], mie->device_submode)) ||
-        (mie->lte_band && !md_zeromq_writer_create_json_int(obj,
+        (mie->lte_band != DEFAULT_LTE_BAND && !md_zeromq_writer_create_json_int(obj,
                 mwz->keys[MD_ZMQ_KEY_LTE_BAND], mie->lte_band)) ||
-        (mie->device_state && !md_zeromq_writer_create_json_int(obj,
+        (mie->device_state != DEFAULT_DEVICE_STATE && !md_zeromq_writer_create_json_int(obj,
                 mwz->keys[MD_ZMQ_KEY_DEVICE_STATE], mie->device_state)) ||
-        (mie->lte_pci != 0xFFFF &&
+        (mie->lte_pci != DEFAULT_LTE_PCI &&
             !md_zeromq_writer_create_json_int(obj,
                 mwz->keys[MD_ZMQ_KEY_LTE_PCI], mie->lte_pci)) ||
-        (mie->enodeb_id >= 0 &&
+        (mie->enodeb_id != DEFAULT_ENODEBID &&
             !md_zeromq_writer_create_json_int(obj,
                 mwz->keys[MD_ZMQ_KEY_ENODEB_ID], mie->enodeb_id))) {
         json_object_put(obj);