diff --git a/lib/include/srslte/upper/rlc_um_base.h b/lib/include/srslte/upper/rlc_um_base.h
index 9bba599ec..8edc8e4c5 100644
--- a/lib/include/srslte/upper/rlc_um_base.h
+++ b/lib/include/srslte/upper/rlc_um_base.h
@@ -135,8 +135,6 @@ protected:
 
     uint32_t& lcid;
 
-    std::mutex mutex;
-
     // helper functions
     virtual void debug_state() = 0;
   };
diff --git a/lib/src/upper/rlc_um_lte.cc b/lib/src/upper/rlc_um_lte.cc
index 851990fd6..e6dbbbb87 100644
--- a/lib/src/upper/rlc_um_lte.cc
+++ b/lib/src/upper/rlc_um_lte.cc
@@ -257,13 +257,11 @@ void rlc_um_lte::rlc_um_lte_rx::reestablish()
     timer_expired(reordering_timer.id());
   }
 
-  std::lock_guard<std::mutex> lock(mutex);
   reset();
 }
 
 void rlc_um_lte::rlc_um_lte_rx::stop()
 {
-  std::lock_guard<std::mutex> lock(mutex);
   reset();
 
   reordering_timer.stop();
@@ -284,8 +282,6 @@ void rlc_um_lte::rlc_um_lte_rx::reset()
 
 void rlc_um_lte::rlc_um_lte_rx::handle_data_pdu(uint8_t* payload, uint32_t nof_bytes)
 {
-  std::lock_guard<std::mutex> lock(mutex);
-
   rlc_umd_pdu_header_t header;
   rlc_um_read_data_pdu_header(payload, nof_bytes, cfg.um.rx_sn_field_length, &header);
   log->info_hex(payload, nof_bytes, "RX %s Rx data PDU SN: %d (%d B)", rb_name.c_str(), header.sn, nof_bytes);
@@ -649,7 +645,6 @@ bool rlc_um_lte::rlc_um_lte_rx::inside_reordering_window(uint16_t sn)
 
 void rlc_um_lte::rlc_um_lte_rx::timer_expired(uint32_t timeout_id)
 {
-  std::lock_guard<std::mutex> lock(mutex);
   if (reordering_timer.id() == timeout_id) {
     // 36.322 v10 Section 5.1.2.2.4
     log->info("%s reordering timeout expiry - updating vr_ur and reassembling\n", rb_name.c_str());
diff --git a/lib/src/upper/rlc_um_nr.cc b/lib/src/upper/rlc_um_nr.cc
index 5bc4924cf..e4cd8fadc 100644
--- a/lib/src/upper/rlc_um_nr.cc
+++ b/lib/src/upper/rlc_um_nr.cc
@@ -245,7 +245,6 @@ bool rlc_um_nr::rlc_um_nr_rx::configure()
 
 void rlc_um_nr::rlc_um_nr_rx::stop()
 {
-  std::lock_guard<std::mutex> lock(mutex);
   reset();
   reassembly_timer.stop();
 }
@@ -277,7 +276,6 @@ void rlc_um_nr::rlc_um_nr_rx::reestablish()
 // TS 38.322 v15.003 Section 5.2.2.2.4
 void rlc_um_nr::rlc_um_nr_rx::timer_expired(uint32_t timeout_id)
 {
-  std::lock_guard<std::mutex> lock(mutex);
   if (reassembly_timer.id() == timeout_id) {
     log->info("%s reassembly timeout expiry - updating RX_Next_Reassembly and reassembling\n", rb_name.c_str());
 
@@ -495,8 +493,6 @@ inline void rlc_um_nr::rlc_um_nr_rx::update_total_sdu_length(rlc_umd_pdu_segment
 // Section 5.2.2.2.2
 void rlc_um_nr::rlc_um_nr_rx::handle_data_pdu(uint8_t* payload, uint32_t nof_bytes)
 {
-  std::lock_guard<std::mutex> lock(mutex);
-
   rlc_um_nr_pdu_header_t header = {};
   rlc_um_nr_read_data_pdu_header(payload, nof_bytes, cfg.um_nr.sn_field_length, &header);
   log->debug_hex(payload, nof_bytes, "RX %s Rx data PDU (%d B)", rb_name.c_str(), nof_bytes);