diff --git a/lib/include/srslte/interfaces/ue_interfaces.h b/lib/include/srslte/interfaces/ue_interfaces.h
index 044bd0983..f2fec0796 100644
--- a/lib/include/srslte/interfaces/ue_interfaces.h
+++ b/lib/include/srslte/interfaces/ue_interfaces.h
@@ -221,7 +221,7 @@ public:
   virtual void reestablish()                                                                    = 0;
   virtual void reestablish(uint32_t lcid)                                                       = 0;
   virtual void reset()                                                                          = 0;
-  virtual void write_sdu(uint32_t lcid, srslte::unique_byte_buffer_t sdu, bool blocking = true) = 0;
+  virtual void write_sdu(uint32_t lcid, srslte::unique_byte_buffer_t sdu, bool blocking = false) = 0;
   virtual void add_bearer(uint32_t lcid, srslte::pdcp_config_t cnfg)                            = 0;
   virtual void change_lcid(uint32_t old_lcid, uint32_t new_lcid)                                = 0;
   virtual void config_security(uint32_t                            lcid,