diff --git a/lib/src/phy/rf/rf_dev.h b/lib/src/phy/rf/rf_dev.h
index 9d3d2de0d..efa8923ae 100644
--- a/lib/src/phy/rf/rf_dev.h
+++ b/lib/src/phy/rf/rf_dev.h
@@ -22,7 +22,7 @@
 /* RF frontend API */
 typedef struct {
   const char *name;
-  char*  (*srslte_rf_devname) (void *h);
+  const char* (*srslte_rf_devname)(void* h);
   int    (*srslte_rf_start_rx_stream)(void *h, bool now);
   int    (*srslte_rf_stop_rx_stream)(void *h);
   void   (*srslte_rf_flush_buffer)(void *h);
diff --git a/lib/src/phy/rf/rf_soapy_imp.c b/lib/src/phy/rf/rf_soapy_imp.c
index 4da0adb93..ddbee1550 100644
--- a/lib/src/phy/rf/rf_soapy_imp.c
+++ b/lib/src/phy/rf/rf_soapy_imp.c
@@ -186,8 +186,7 @@ void rf_soapy_register_error_handler(void *h, srslte_rf_error_handler_t new_hand
   handler->soapy_error_handler = new_handler;
 }
 
-
-char* rf_soapy_devname(void* h)
+const char* rf_soapy_devname(void* h)
 {
   rf_soapy_handler_t *handler = (rf_soapy_handler_t*) h;
   return handler->devname;
@@ -209,9 +208,7 @@ void rf_soapy_calibrate_tx(void *h)
   char str_buf[25];
   snprintf(str_buf, sizeof(str_buf), "%f", actual_bw);
   str_buf[24] = 0;
-  if (SoapySDRDevice_writeSetting(handler->device, "CALIBRATE_TX", str_buf)) {
-    printf("Error calibrating Rx\n");
-  }
+  SoapySDRDevice_writeSetting(handler->device, "CALIBRATE_TX", str_buf);
 }
 
 int rf_soapy_start_rx_stream(void *h, bool now)
diff --git a/lib/src/phy/rf/rf_soapy_imp.h b/lib/src/phy/rf/rf_soapy_imp.h
index 155dd3aec..d90ed6a56 100644
--- a/lib/src/phy/rf/rf_soapy_imp.h
+++ b/lib/src/phy/rf/rf_soapy_imp.h
@@ -32,7 +32,7 @@ SRSLTE_API int rf_soapy_open(char *args,
 
 SRSLTE_API int rf_soapy_open_multi(char* args, void** handler, uint32_t num_requested_channels);
 
-SRSLTE_API char* rf_soapy_devname(void *h);
+SRSLTE_API const char* rf_soapy_devname(void* h);
 
 SRSLTE_API int rf_soapy_close(void *h);
 
diff --git a/lib/src/phy/rf/rf_uhd_imp.c b/lib/src/phy/rf/rf_uhd_imp.c
index c3473e28d..e5633e6bd 100644
--- a/lib/src/phy/rf/rf_uhd_imp.c
+++ b/lib/src/phy/rf/rf_uhd_imp.c
@@ -226,7 +226,7 @@ wait_sensor_locked(rf_uhd_handler_t* handler, char* sensor_name, bool is_mboard,
   return error;
 }
 
-char* rf_uhd_devname(void* h)
+const char* rf_uhd_devname(void* h)
 {
   rf_uhd_handler_t* handler = (rf_uhd_handler_t*)h;
   return handler->devname;
diff --git a/lib/src/phy/rf/rf_uhd_imp.h b/lib/src/phy/rf/rf_uhd_imp.h
index 34aac195d..49c85ea13 100644
--- a/lib/src/phy/rf/rf_uhd_imp.h
+++ b/lib/src/phy/rf/rf_uhd_imp.h
@@ -38,7 +38,7 @@ SRSLTE_API int rf_uhd_open_multi(char *args,
                                  void **handler, 
                                  uint32_t nof_channels);
 
-SRSLTE_API char* rf_uhd_devname(void *h);
+SRSLTE_API const char* rf_uhd_devname(void* h);
 
 SRSLTE_API int rf_uhd_close(void *h);
 
diff --git a/lib/src/phy/rf/rf_zmq_imp.c b/lib/src/phy/rf/rf_zmq_imp.c
index af6c19b5e..7497db701 100644
--- a/lib/src/phy/rf/rf_zmq_imp.c
+++ b/lib/src/phy/rf/rf_zmq_imp.c
@@ -157,9 +157,9 @@ void rf_zmq_register_error_handler(void* h, srslte_rf_error_handler_t new_handle
   // do nothing
 }
 
-char* rf_zmq_devname(void* h)
+const char* rf_zmq_devname(void* h)
 {
-  return (char*)zmq_devname;
+  return zmq_devname;
 }
 
 int rf_zmq_start_rx_stream(void* h, bool now)
diff --git a/lib/src/phy/rf/rf_zmq_imp.h b/lib/src/phy/rf/rf_zmq_imp.h
index cab2f68e6..d8758fba4 100644
--- a/lib/src/phy/rf/rf_zmq_imp.h
+++ b/lib/src/phy/rf/rf_zmq_imp.h
@@ -33,7 +33,7 @@ SRSLTE_API int rf_zmq_open(char* args, void** handler);
 
 SRSLTE_API int rf_zmq_open_multi(char* args, void** handler, uint32_t nof_channels);
 
-SRSLTE_API char* rf_zmq_devname(void* h);
+SRSLTE_API const char* rf_zmq_devname(void* h);
 
 SRSLTE_API int rf_zmq_close(void* h);