diff --git a/lib/src/phy/rf/rf_zmq_imp.c b/lib/src/phy/rf/rf_zmq_imp.c
index 80cd55705..2f8bdcdbc 100644
--- a/lib/src/phy/rf/rf_zmq_imp.c
+++ b/lib/src/phy/rf/rf_zmq_imp.c
@@ -64,6 +64,7 @@ typedef struct {
 
   pthread_mutex_t tx_config_mutex;
   pthread_mutex_t rx_config_mutex;
+  pthread_mutex_t decim_mutex;
 } rf_zmq_handler_t;
 
 void update_rates(rf_zmq_handler_t* handler, double srate);
@@ -242,6 +243,9 @@ int rf_zmq_open_multi(char* args, void** h, uint32_t nof_channels)
     if (pthread_mutex_init(&handler->rx_config_mutex, NULL)) {
       perror("Mutex init");
     }
+    if (pthread_mutex_init(&handler->decim_mutex, NULL)) {
+      perror("Mutex init");
+    }
 
     // parse args
     if (args && strlen(args)) {
@@ -524,6 +528,7 @@ int rf_zmq_close(void* h)
 
   pthread_mutex_destroy(&handler->tx_config_mutex);
   pthread_mutex_destroy(&handler->rx_config_mutex);
+  pthread_mutex_destroy(&handler->decim_mutex);
 
   // Free all
   free(handler);
@@ -533,6 +538,7 @@ int rf_zmq_close(void* h)
 
 void update_rates(rf_zmq_handler_t* handler, double srate)
 {
+  pthread_mutex_lock(&handler->decim_mutex);
   if (handler) {
     // Decimation must be full integer
     if (((uint64_t)handler->base_srate % (uint64_t)srate) == 0) {
@@ -549,6 +555,7 @@ void update_rates(rf_zmq_handler_t* handler, double srate)
            handler->base_srate / 1e6,
            handler->decim_factor);
   }
+  pthread_mutex_unlock(&handler->decim_mutex);
 }
 
 double rf_zmq_set_rx_srate(void* h, double srate)
@@ -715,11 +722,6 @@ int rf_zmq_recv_with_time_multi(void*    h,
   if (h) {
     rf_zmq_handler_t* handler = (rf_zmq_handler_t*)h;
 
-    uint32_t nbytes            = NSAMPLES2NBYTES(nsamples * handler->decim_factor);
-    uint32_t nsamples_baserate = nsamples * handler->decim_factor;
-
-    rf_zmq_info(handler->id, "Rx %d samples (%d B)\n", nsamples, nbytes);
-
     // Map ports to data buffers according to the selected frequencies
     pthread_mutex_lock(&handler->rx_config_mutex);
     cf_t* buffers[SRSLTE_MAX_PORTS] = {}; // Buffer pointers, NULL if unmatched
@@ -743,6 +745,16 @@ int rf_zmq_recv_with_time_multi(void*    h,
     }
     pthread_mutex_unlock(&handler->rx_config_mutex);
 
+    // Protect the access to decim_factor since is a shared variable
+    pthread_mutex_lock(&handler->decim_mutex);
+    uint32_t decim_factor = handler->decim_factor;
+    pthread_mutex_unlock(&handler->decim_mutex);
+
+    uint32_t nbytes            = NSAMPLES2NBYTES(nsamples * decim_factor);
+    uint32_t nsamples_baserate = nsamples * decim_factor;
+
+    rf_zmq_info(handler->id, "Rx %d samples (%d B)\n", nsamples, nbytes);
+
     // set timestamp for this reception
     if (secs != NULL && frac_secs != NULL) {
       srslte_timestamp_t ts = {};
@@ -792,7 +804,7 @@ int rf_zmq_recv_with_time_multi(void*    h,
 
       // Iterate channels
       for (uint32_t i = 0; i < handler->nof_channels; i++) {
-        cf_t* ptr = (handler->decim_factor != 1 || buffers[i] == NULL) ? handler->buffer_decimation[i] : buffers[i];
+        cf_t* ptr = (decim_factor != 1 || buffers[i] == NULL) ? handler->buffer_decimation[i] : buffers[i];
 
         // Completed condition
         if (count[i] < nsamples_baserate && handler->receiver[i].running) {
@@ -843,7 +855,7 @@ int rf_zmq_recv_with_time_multi(void*    h,
                 NBYTES2NSAMPLES(srslte_ringbuffer_status(&handler->receiver[0].ringbuffer)));
 
     // decimate if needed
-    if (handler->decim_factor != 1) {
+    if (decim_factor != 1) {
       for (uint32_t c = 0; c < handler->nof_channels; c++) {
         // skip if buffer is not available
         if (buffers[c]) {
@@ -853,7 +865,7 @@ int rf_zmq_recv_with_time_multi(void*    h,
           for (uint32_t i = 0, n = 0; i < nsamples; i++) {
             // Averaging decimation
             cf_t avg = 0.0f;
-            for (int j = 0; j < handler->decim_factor; j++, n++) {
+            for (int j = 0; j < decim_factor; j++, n++) {
               avg += ptr[n];
             }
             dst[i] = avg;
@@ -861,7 +873,7 @@ int rf_zmq_recv_with_time_multi(void*    h,
 
           rf_zmq_info(handler->id,
                       "  - re-adjust bytes due to %dx decimation %d --> %d samples)\n",
-                      handler->decim_factor,
+                      decim_factor,
                       nsamples_baserate,
                       nsamples);
         }
@@ -918,14 +930,6 @@ int rf_zmq_send_timed_multi(void*  h,
 
   if (h && data && nsamples > 0) {
     rf_zmq_handler_t* handler           = (rf_zmq_handler_t*)h;
-    uint32_t          nbytes            = NSAMPLES2NBYTES(nsamples);
-    uint32_t          nsamples_baseband = nsamples * handler->decim_factor;
-    uint32_t          nbytes_baseband   = NSAMPLES2NBYTES(nsamples_baseband);
-
-    if (nbytes_baseband > ZMQ_MAX_BUFFER_SIZE) {
-      fprintf(stderr, "Error: trying to transmit too many samples (%d > %zu).\n", nbytes, ZMQ_MAX_BUFFER_SIZE);
-      goto clean_exit;
-    }
 
     // Map ports to data buffers according to the selected frequencies
     pthread_mutex_lock(&handler->tx_config_mutex);
@@ -945,6 +949,19 @@ int rf_zmq_send_timed_multi(void*  h,
     }
     pthread_mutex_unlock(&handler->tx_config_mutex);
 
+    // Protect the access to decim_factor since is a shared variable
+    pthread_mutex_lock(&handler->decim_mutex);
+    uint32_t decim_factor = handler->decim_factor;
+    pthread_mutex_unlock(&handler->decim_mutex);
+
+    uint32_t nbytes            = NSAMPLES2NBYTES(nsamples);
+    uint32_t nsamples_baseband = nsamples * decim_factor;
+    uint32_t nbytes_baseband   = NSAMPLES2NBYTES(nsamples_baseband);
+    if (nbytes_baseband > ZMQ_MAX_BUFFER_SIZE) {
+      fprintf(stderr, "Error: trying to transmit too many samples (%d > %zu).\n", nbytes, ZMQ_MAX_BUFFER_SIZE);
+      goto clean_exit;
+    }
+
     rf_zmq_info(handler->id, "Tx %d samples (%d B)\n", nsamples, nbytes);
 
     // return if transmitter is switched off
@@ -981,13 +998,13 @@ int rf_zmq_send_timed_multi(void*  h,
     for (int i = 0; i < handler->nof_channels; i++) {
       if (buffers[i] != NULL) {
         // Select buffer pointer depending on interpolation
-        cf_t* buf = (handler->decim_factor != 1) ? handler->buffer_tx : buffers[i];
+        cf_t* buf = (decim_factor != 1) ? handler->buffer_tx : buffers[i];
 
         // Interpolate if required
-        if (handler->decim_factor != 1) {
+        if (decim_factor != 1) {
           rf_zmq_info(handler->id,
                       "  - re-adjust bytes due to %dx interpolation %d --> %d samples)\n",
-                      handler->decim_factor,
+                      decim_factor,
                       nsamples,
                       nsamples_baseband);
 
@@ -995,7 +1012,7 @@ int rf_zmq_send_timed_multi(void*  h,
           cf_t* src = data[i];
           for (int k = 0; k < nsamples; k++) {
             // perform zero order hold
-            for (int j = 0; j < handler->decim_factor; j++, n++) {
+            for (int j = 0; j < decim_factor; j++, n++) {
               buf[n] = src[k];
             }
           }
diff --git a/srsue/src/phy/sync.cc b/srsue/src/phy/sync.cc
index a9f45a56a..63b1680ae 100644
--- a/srsue/src/phy/sync.cc
+++ b/srsue/src/phy/sync.cc
@@ -374,8 +374,12 @@ void sync::run_thread()
 
   cf_t*    dummy_buffer[SRSLTE_MAX_PORTS];
   uint32_t nof_rf_channels = worker_com->args->nof_rf_channels * worker_com->args->nof_rx_ant;
+  if (nof_rf_channels > SRSLTE_MAX_PORTS) {
+    fprintf(stderr, "Fatal error: nof_rf_channels x nof_rx_ant must be lower than %d\n", SRSLTE_MAX_PORTS);
+    return;
+  }
   for (uint32_t i = 0; i < nof_rf_channels; i++) {
-    dummy_buffer[i] = (cf_t*)malloc(sizeof(cf_t) * SRSLTE_SF_LEN_PRB(100));
+    dummy_buffer[i] = (cf_t*)srslte_vec_cf_malloc(3 * SRSLTE_SF_LEN_PRB(100));
   }
 
   uint32_t prach_nof_sf = 0;