diff --git a/rtl/ibex_cs_registers.sv b/rtl/ibex_cs_registers.sv
index 15329807..67e59785 100644
--- a/rtl/ibex_cs_registers.sv
+++ b/rtl/ibex_cs_registers.sv
@@ -124,14 +124,14 @@ module ibex_cs_registers #(
 
   import ibex_pkg::*;
 
-  localparam int unsigned RV32BEnabled = (RV32B == RV32BNone) ? 0 : 1;
+  localparam int unsigned RV32BExtra = (RV32B == RV32BOTEarlGrey) || (RV32B == RV32BFull) ? 1 : 0;
   localparam int unsigned RV32MEnabled = (RV32M == RV32MNone) ? 0 : 1;
   localparam int unsigned PMPAddrWidth = (PMPGranularity > 0) ? 33 - PMPGranularity : 32;
 
   // misa
   localparam logic [31:0] MISA_VALUE =
       (0                 <<  0)  // A - Atomic Instructions extension
-    | (RV32BEnabled      <<  1)  // B - Bit-Manipulation extension
+    | (0                 <<  1)  // B - Bit-Manipulation extension
     | (1                 <<  2)  // C - Compressed extension
     | (0                 <<  3)  // D - Double precision floating-point extension
     | (32'(RV32E)        <<  4)  // E - RV32E base ISA
@@ -141,7 +141,7 @@ module ibex_cs_registers #(
     | (0                 << 13)  // N - User level interrupts supported
     | (0                 << 18)  // S - Supervisor mode implemented
     | (1                 << 20)  // U - User mode implemented
-    | (0                 << 23)  // X - Non-standard extensions present
+    | (RV32BExtra        << 23)  // X - Non-standard extensions present
     | (32'(CSR_MISA_MXL) << 30); // M-XLEN
 
   typedef struct packed {