diff --git a/hw/ip/otbn/rtl/otbn_controller.sv b/hw/ip/otbn/rtl/otbn_controller.sv
index c2e1af0..6da7c23 100644
--- a/hw/ip/otbn/rtl/otbn_controller.sv
+++ b/hw/ip/otbn/rtl/otbn_controller.sv
@@ -374,7 +374,7 @@
   `ASSERT(ErrSetOnFatalErr, fatal_err |-> err)
 
   `ASSERT(ControllerStateValid, state_q inside {OtbnStateHalt, OtbnStateRun,
-                                                OtbnStateStall})
+                                                OtbnStateStall, OtbnStateLocked})
   // Branch only takes effect in OtbnStateRun so must not go into stall state for branch
   // instructions.
   `ASSERT(NoStallOnBranch,