diff --git a/target/riscv/tcg/tcg-cpu.c b/target/riscv/tcg/tcg-cpu.c
index 683f604d9f..fa8a17cc60 100644
--- a/target/riscv/tcg/tcg-cpu.c
+++ b/target/riscv/tcg/tcg-cpu.c
@@ -667,6 +667,10 @@ void riscv_cpu_validate_set_extensions(RISCVCPU *cpu, Error **errp)
         cpu_cfg_ext_auto_update(cpu, CPU_CFG_OFFSET(ext_zvbc), true);
     }
 
+    if (cpu->cfg.ext_zvbb) {
+        cpu_cfg_ext_auto_update(cpu, CPU_CFG_OFFSET(ext_zvkb), true);
+    }
+
     if ((cpu->cfg.ext_zvbb || cpu->cfg.ext_zvkb || cpu->cfg.ext_zvkg ||
          cpu->cfg.ext_zvkned || cpu->cfg.ext_zvknha || cpu->cfg.ext_zvksed ||
          cpu->cfg.ext_zvksh) && !cpu->cfg.ext_zve32x) {