diff --git a/openrtx/src/rtx/OpMode_M17.cpp b/openrtx/src/rtx/OpMode_M17.cpp
index 587eb764..2d4ffc9e 100644
--- a/openrtx/src/rtx/OpMode_M17.cpp
+++ b/openrtx/src/rtx/OpMode_M17.cpp
@@ -77,9 +77,9 @@ void OpMode_M17::update(rtxStatus_t *const status, const bool newCfg)
             audio_enableMic();
             radio_enableTx();
 
-            // TODO: Allow destinations different than broadcast
-            std::string source_address("OPNRTX");
-            m17Tx.start(source_address);
+            std::string source_address(status->source_address);
+            std::string destination_address(status->destination_address);
+            m17Tx.start(source_address, destination_address);
 
             status->opStatus = TX;
         }
diff --git a/openrtx/src/rtx/rtx.cpp b/openrtx/src/rtx/rtx.cpp
index f1d42d39..6ecfae66 100644
--- a/openrtx/src/rtx/rtx.cpp
+++ b/openrtx/src/rtx/rtx.cpp
@@ -24,18 +24,18 @@
 #include <OpMode_FM.h>
 #include <OpMode_M17.h>
 
-pthread_mutex_t *cfgMutex;  // Mutex for incoming config messages
+pthread_mutex_t *cfgMutex;      // Mutex for incoming config messages
 
-const rtxStatus_t *newCnf;  // Pointer for incoming config messages
-rtxStatus_t rtxStatus;      // RTX driver status
+const rtxStatus_t *newCnf;      // Pointer for incoming config messages
+rtxStatus_t rtxStatus = { 0 };  // RTX driver status
 
-float rssi;                 // Current RSSI in dBm
-bool  reinitFilter;         // Flag for RSSI filter re-initialisation
+float rssi;                     // Current RSSI in dBm
+bool  reinitFilter;             // Flag for RSSI filter re-initialisation
 
-OpMode  *currMode;          // Pointer to currently active opMode handler
-OpMode     noMode;          // Empty opMode handler for opmode::NONE
-OpMode_FM  fmMode;          // FM mode handler
-OpMode_M17 m17Mode;         // M17 mode handler
+OpMode  *currMode;              // Pointer to currently active opMode handler
+OpMode     noMode;              // Empty opMode handler for opmode::NONE
+OpMode_FM  fmMode;              // FM mode handler
+OpMode_M17 m17Mode;             // M17 mode handler
 
 void rtx_init(pthread_mutex_t *m)
 {
diff --git a/openrtx/src/state.c b/openrtx/src/state.c
index d2e1d410..564edbf5 100644
--- a/openrtx/src/state.c
+++ b/openrtx/src/state.c
@@ -82,6 +82,9 @@ void state_init()
 
     state.emergency = false;
 
+    // Initialize M17_data
+    strncpy(state.m17_data.callsign, "OPNRTX", 10);
+
     // Read settings from flash memory
     // NOTE: Disable reading VFO from flash until persistence is implemented
     //int valid = nvm_readSettings(&state.settings);
diff --git a/openrtx/src/threads.c b/openrtx/src/threads.c
index d926228c..ded227e4 100644
--- a/openrtx/src/threads.c
+++ b/openrtx/src/threads.c
@@ -103,6 +103,10 @@ void *ui_task(void *arg)
             rtx_cfg.txTone = ctcss_tone[state.channel.fm.txTone];
             pthread_mutex_unlock(&rtx_mutex);
 
+            // Copy new M17 source and destination addresses
+            strncpy(rtx_cfg.source_address, state.m17_data.callsign, 10);
+            strncpy(rtx_cfg.destination_address, "", 10);
+
             rtx_configure(&rtx_cfg);
             sync_rtx = false;
         }
diff --git a/openrtx/src/ui/ui.c b/openrtx/src/ui/ui.c
index 27645c3b..fe7ec405 100644
--- a/openrtx/src/ui/ui.c
+++ b/openrtx/src/ui/ui.c
@@ -1324,8 +1324,9 @@ void ui_updateFSM(event_t event, bool *sync_rtx)
                     {
                         _ui_textInputConfirm(ui_state.new_callsign);
                         // Save selected callsign and disable input mode
-                        strcpy(state.m17_data.callsign, ui_state.new_callsign);
+                        strncpy(state.m17_data.callsign, ui_state.new_callsign, 10);
                         ui_state.edit_mode = false;
+                        *sync_rtx = true;
                     }
                     else if(msg.keys & KEY_ESC)
                         // Discard selected callsign and disable input mode