diff --git a/hw/ip/otbn/rtl/otbn.sv b/hw/ip/otbn/rtl/otbn.sv
index 1cb0934078def..4c324d13338ba 100644
--- a/hw/ip/otbn/rtl/otbn.sv
+++ b/hw/ip/otbn/rtl/otbn.sv
@@ -1213,6 +1213,7 @@ module otbn
   `ASSERT_KNOWN(EdnRndOKnown_A, edn_rnd_o, clk_edn_i, !rst_edn_ni)
   `ASSERT_KNOWN(EdnUrndOKnown_A, edn_urnd_o, clk_edn_i, !rst_edn_ni)
   `ASSERT_KNOWN(OtbnOtpKeyO_A, otbn_otp_key_o, clk_otp_i, !rst_otp_ni)
+  `ASSERT_KNOWN(ErrBitsKnown_A, err_bits)
 
   // Incoming key must be valid (other inputs go via prim modules that handle the X checks).
   `ASSERT_KNOWN(KeyMgrKeyValid_A, keymgr_key_i.valid)
diff --git a/hw/ip/otbn/rtl/otbn_core.sv b/hw/ip/otbn/rtl/otbn_core.sv
index 1b411751bd288..d624d9e0acc33 100644
--- a/hw/ip/otbn/rtl/otbn_core.sv
+++ b/hw/ip/otbn/rtl/otbn_core.sv
@@ -906,6 +906,7 @@ module otbn_core
   `ASSERT_KNOWN(EdnRndReqOKnown_A, edn_rnd_req_o)
   `ASSERT_KNOWN(EdnUrndReqOKnown_A, edn_urnd_req_o)
   `ASSERT_KNOWN(InsnCntOKnown_A, insn_cnt_o)
+  `ASSERT_KNOWN(ErrBitsKnown_A, err_bits_o)
 
   // Keep the EDN requests active until they are acknowledged.
   `ASSERT(EdnRndReqStable_A, edn_rnd_req_o & ~edn_rnd_ack_i |=> edn_rnd_req_o)