diff --git a/qemu/target-i386/helper.h b/qemu/target-i386/helper.h
index 294d4dca..1c0afcf6 100644
--- a/qemu/target-i386/helper.h
+++ b/qemu/target-i386/helper.h
@@ -3,8 +3,6 @@ DEF_HELPER_4(uc_tracecode, void, i32, i32, ptr, i64)
 DEF_HELPER_FLAGS_4(cc_compute_all, TCG_CALL_NO_RWG_SE, tl, tl, tl, tl, int)
 DEF_HELPER_FLAGS_4(cc_compute_c, TCG_CALL_NO_RWG_SE, tl, tl, tl, tl, int)
 
-DEF_HELPER_1(lock, void, env)
-DEF_HELPER_1(unlock, void, env)
 DEF_HELPER_3(write_eflags, void, env, tl, i32)
 DEF_HELPER_1(read_eflags, tl, env)
 DEF_HELPER_2(divb_AL, void, env, tl)
diff --git a/qemu/target-i386/mem_helper.c b/qemu/target-i386/mem_helper.c
index e569d5e6..dc60b056 100644
--- a/qemu/target-i386/mem_helper.c
+++ b/qemu/target-i386/mem_helper.c
@@ -27,16 +27,6 @@
 
 #include "uc_priv.h"
 
-/* broken thread support */
-
-void helper_lock(CPUX86State *env)
-{
-}
-
-void helper_unlock(CPUX86State *env)
-{
-}
-
 void helper_cmpxchg8b_unlocked(CPUX86State *env, target_ulong a0)
 {
     uintptr_t ra = GETPC();
diff --git a/qemu/target-i386/translate.c b/qemu/target-i386/translate.c
index 41f0c138..65048418 100644
--- a/qemu/target-i386/translate.c
+++ b/qemu/target-i386/translate.c
@@ -5184,10 +5184,6 @@ static target_ulong disas_insn(CPUX86State *env, DisasContext *s,
     s->aflag = aflag;
     s->dflag = dflag;
 
-    /* lock generation */
-    if (prefixes & PREFIX_LOCK)
-        gen_helper_lock(tcg_ctx, cpu_env);
-
     /* now check op code */
  reswitch:
     switch(b) {
@@ -8947,9 +8943,6 @@ case 0x101:
     default:
         goto unknown_op;
     }
-    /* lock generation */
-    if (s->prefix & PREFIX_LOCK)
-        gen_helper_unlock(tcg_ctx, cpu_env);
 
     // Unicorn: patch the callback for the instruction size
     if (HOOK_EXISTS_BOUNDED(env->uc, UC_HOOK_CODE, pc_start)) {
@@ -8975,15 +8968,9 @@ case 0x101:
 
     return s->pc;
  illegal_op:
-    if (s->prefix & PREFIX_LOCK)
-        gen_helper_unlock(tcg_ctx, cpu_env);
-    /* XXX: ensure that no lock was generated */
     gen_illegal_opcode(s);
     return s->pc;
  unknown_op:
-    if (s->prefix & PREFIX_LOCK)
-        gen_helper_unlock(tcg_ctx, cpu_env);
-    /* XXX: ensure that no lock was generated */
     gen_unknown_opcode(env, s);
     return s->pc;
 }