diff --git a/srsue/hdr/stack/mac_nr/proc_sr_nr.h b/srsue/hdr/stack/mac_nr/proc_sr_nr.h
index 1d0224350..ab57b0a5e 100644
--- a/srsue/hdr/stack/mac_nr/proc_sr_nr.h
+++ b/srsue/hdr/stack/mac_nr/proc_sr_nr.h
@@ -13,10 +13,11 @@
 #ifndef SRSUE_PROC_SR_NR_H
 #define SRSUE_PROC_SR_NR_H
 
-#include "srsue/hdr/stack/mac_nr/mac_nr_interfaces.h"
 #include "srsran/interfaces/ue_mac_interfaces.h"
 #include "srsran/interfaces/ue_nr_interfaces.h"
 #include "srsran/srslog/srslog.h"
+#include "srsue/hdr/stack/mac_nr/mac_nr_interfaces.h"
+#include <mutex>
 #include <stdint.h>
 
 /// Scheduling Request procedure as defined in 5.4.4 of 38.321
@@ -39,6 +40,7 @@ public:
   bool    sr_opportunity(uint32_t tti, uint32_t sr_id, bool meas_gap, bool ul_sch_tx);
 
 private:
+  void reset_unsafe();
   int  sr_counter    = 0;
   bool is_pending_sr = false;
 
@@ -49,7 +51,8 @@ private:
   phy_interface_mac_nr* phy = nullptr;
   srslog::basic_logger& logger;
 
-  bool initiated = false;
+  bool       initiated = false;
+  std::mutex mutex;
 };
 
 } // namespace srsue
diff --git a/srsue/src/stack/mac_nr/proc_sr_nr.cc b/srsue/src/stack/mac_nr/proc_sr_nr.cc
index a35db5c69..e68b0483b 100644
--- a/srsue/src/stack/mac_nr/proc_sr_nr.cc
+++ b/srsue/src/stack/mac_nr/proc_sr_nr.cc
@@ -21,6 +21,7 @@ proc_sr_nr::proc_sr_nr(srslog::basic_logger& logger) : logger(logger) {}
 
 int32_t proc_sr_nr::init(mac_interface_sr_nr* mac_, phy_interface_mac_nr* phy_, rrc_interface_mac* rrc_)
 {
+  std::lock_guard<std::mutex> lock(mutex);
   rrc        = rrc_;
   mac        = mac_;
   phy        = phy_;
@@ -32,6 +33,12 @@ int32_t proc_sr_nr::init(mac_interface_sr_nr* mac_, phy_interface_mac_nr* phy_,
 }
 
 void proc_sr_nr::reset()
+{
+  std::lock_guard<std::mutex> lock(mutex);
+  reset_unsafe();
+}
+
+void proc_sr_nr::reset_unsafe()
 {
   is_pending_sr = false;
 }
@@ -70,6 +77,7 @@ int32_t proc_sr_nr::set_config(const srsran::sr_cfg_nr_t& cfg_)
 
 void proc_sr_nr::step(uint32_t tti)
 {
+  std::lock_guard<std::mutex> lock(mutex);
   if (!initiated) {
     return;
   }
@@ -84,7 +92,7 @@ void proc_sr_nr::step(uint32_t tti)
     // 2> initiate a Random Access procedure (see clause 5.1) on the SpCell and cancel the pending SR.
     logger.info("SR:    PUCCH not configured. Starting RA procedure");
     mac->start_ra();
-    reset();
+    reset_unsafe();
     return;
   }
 
@@ -102,12 +110,13 @@ void proc_sr_nr::step(uint32_t tti)
     // ... TODO
 
     mac->start_ra();
-    reset();
+    reset_unsafe();
   }
 }
 
 bool proc_sr_nr::sr_opportunity(uint32_t tti, uint32_t sr_id, bool meas_gap, bool ul_sch_tx)
 {
+  std::lock_guard<std::mutex> lock(mutex);
   // 2> when the MAC entity has an SR transmission occasion on the valid PUCCH resource for SR configured; and
   if (!initiated || !cfg.enabled || !is_pending_sr) {
     return false;
@@ -147,6 +156,7 @@ bool proc_sr_nr::sr_opportunity(uint32_t tti, uint32_t sr_id, bool meas_gap, boo
 
 void proc_sr_nr::start()
 {
+  std::lock_guard<std::mutex> lock(mutex);
   if (initiated) {
     if (not is_pending_sr) {
       logger.info("SR:    Starting procedure");