diff --git a/target-i386/cpu.h b/target-i386/cpu.h
index 4585c0a..28ff02d 100644
--- a/target-i386/cpu.h
+++ b/target-i386/cpu.h
@@ -1105,8 +1105,6 @@ static inline int cpu_mmu_index (CPUX86State *env)
 #define ECX (env->regs[R_ECX])
 #undef EDX
 #define EDX (env->regs[R_EDX])
-#undef EBX
-#define EBX (env->regs[R_EBX])
 #undef ESP
 #define ESP (env->regs[R_ESP])
 #undef EBP
diff --git a/target-i386/mem_helper.c b/target-i386/mem_helper.c
index f0f5aec..6370fb5 100644
--- a/target-i386/mem_helper.c
+++ b/target-i386/mem_helper.c
@@ -46,7 +46,7 @@ void helper_cmpxchg8b(CPUX86State *env, target_ulong a0)
     eflags = cpu_cc_compute_all(env, CC_OP);
     d = cpu_ldq_data(env, a0);
     if (d == (((uint64_t)EDX << 32) | (uint32_t)env->regs[R_EAX])) {
-        cpu_stq_data(env, a0, ((uint64_t)ECX << 32) | (uint32_t)EBX);
+        cpu_stq_data(env, a0, ((uint64_t)ECX << 32) | (uint32_t)env->regs[R_EBX]);
         eflags |= CC_Z;
     } else {
         /* always do the store */
@@ -71,7 +71,7 @@ void helper_cmpxchg16b(CPUX86State *env, target_ulong a0)
     d0 = cpu_ldq_data(env, a0);
     d1 = cpu_ldq_data(env, a0 + 8);
     if (d0 == env->regs[R_EAX] && d1 == EDX) {
-        cpu_stq_data(env, a0, EBX);
+        cpu_stq_data(env, a0, env->regs[R_EBX]);
         cpu_stq_data(env, a0 + 8, ECX);
         eflags |= CC_Z;
     } else {
diff --git a/target-i386/misc_helper.c b/target-i386/misc_helper.c
index a6a787f..d7be4f4 100644
--- a/target-i386/misc_helper.c
+++ b/target-i386/misc_helper.c
@@ -124,7 +124,7 @@ void helper_cpuid(CPUX86State *env)
 
     cpu_x86_cpuid(env, (uint32_t)env->regs[R_EAX], (uint32_t)ECX, &eax, &ebx, &ecx, &edx);
     env->regs[R_EAX] = eax;
-    EBX = ebx;
+    env->regs[R_EBX] = ebx;
     ECX = ecx;
     EDX = edx;
 }
diff --git a/target-i386/seg_helper.c b/target-i386/seg_helper.c
index 719b7bb..b3c087f 100644
--- a/target-i386/seg_helper.c
+++ b/target-i386/seg_helper.c
@@ -327,7 +327,7 @@ static void switch_tss(CPUX86State *env, int tss_selector,
         cpu_stl_kernel(env, env->tr.base + (0x28 + 0 * 4), env->regs[R_EAX]);
         cpu_stl_kernel(env, env->tr.base + (0x28 + 1 * 4), ECX);
         cpu_stl_kernel(env, env->tr.base + (0x28 + 2 * 4), EDX);
-        cpu_stl_kernel(env, env->tr.base + (0x28 + 3 * 4), EBX);
+        cpu_stl_kernel(env, env->tr.base + (0x28 + 3 * 4), env->regs[R_EBX]);
         cpu_stl_kernel(env, env->tr.base + (0x28 + 4 * 4), ESP);
         cpu_stl_kernel(env, env->tr.base + (0x28 + 5 * 4), EBP);
         cpu_stl_kernel(env, env->tr.base + (0x28 + 6 * 4), ESI);
@@ -343,7 +343,7 @@ static void switch_tss(CPUX86State *env, int tss_selector,
         cpu_stw_kernel(env, env->tr.base + (0x12 + 0 * 2), env->regs[R_EAX]);
         cpu_stw_kernel(env, env->tr.base + (0x12 + 1 * 2), ECX);
         cpu_stw_kernel(env, env->tr.base + (0x12 + 2 * 2), EDX);
-        cpu_stw_kernel(env, env->tr.base + (0x12 + 3 * 2), EBX);
+        cpu_stw_kernel(env, env->tr.base + (0x12 + 3 * 2), env->regs[R_EBX]);
         cpu_stw_kernel(env, env->tr.base + (0x12 + 4 * 2), ESP);
         cpu_stw_kernel(env, env->tr.base + (0x12 + 5 * 2), EBP);
         cpu_stw_kernel(env, env->tr.base + (0x12 + 6 * 2), ESI);
@@ -399,7 +399,7 @@ static void switch_tss(CPUX86State *env, int tss_selector,
     env->regs[R_EAX] = new_regs[0];
     ECX = new_regs[1];
     EDX = new_regs[2];
-    EBX = new_regs[3];
+    env->regs[R_EBX] = new_regs[3];
     ESP = new_regs[4];
     EBP = new_regs[5];
     ESI = new_regs[6];
diff --git a/target-i386/smm_helper.c b/target-i386/smm_helper.c
index 1ea6107..28c78a5 100644
--- a/target-i386/smm_helper.c
+++ b/target-i386/smm_helper.c
@@ -85,7 +85,7 @@ void do_smm_enter(CPUX86State *env)
     stq_phys(sm_state + 0x7ff8, env->regs[R_EAX]);
     stq_phys(sm_state + 0x7ff0, ECX);
     stq_phys(sm_state + 0x7fe8, EDX);
-    stq_phys(sm_state + 0x7fe0, EBX);
+    stq_phys(sm_state + 0x7fe0, env->regs[R_EBX]);
     stq_phys(sm_state + 0x7fd8, ESP);
     stq_phys(sm_state + 0x7fd0, EBP);
     stq_phys(sm_state + 0x7fc8, ESI);
@@ -113,7 +113,7 @@ void do_smm_enter(CPUX86State *env)
     stl_phys(sm_state + 0x7fe8, ESI);
     stl_phys(sm_state + 0x7fe4, EBP);
     stl_phys(sm_state + 0x7fe0, ESP);
-    stl_phys(sm_state + 0x7fdc, EBX);
+    stl_phys(sm_state + 0x7fdc, env->regs[R_EBX]);
     stl_phys(sm_state + 0x7fd8, EDX);
     stl_phys(sm_state + 0x7fd4, ECX);
     stl_phys(sm_state + 0x7fd0, env->regs[R_EAX]);
@@ -216,7 +216,7 @@ void helper_rsm(CPUX86State *env)
     env->regs[R_EAX] = ldq_phys(sm_state + 0x7ff8);
     ECX = ldq_phys(sm_state + 0x7ff0);
     EDX = ldq_phys(sm_state + 0x7fe8);
-    EBX = ldq_phys(sm_state + 0x7fe0);
+    env->regs[R_EBX] = ldq_phys(sm_state + 0x7fe0);
     ESP = ldq_phys(sm_state + 0x7fd8);
     EBP = ldq_phys(sm_state + 0x7fd0);
     ESI = ldq_phys(sm_state + 0x7fc8);
@@ -248,7 +248,7 @@ void helper_rsm(CPUX86State *env)
     ESI = ldl_phys(sm_state + 0x7fe8);
     EBP = ldl_phys(sm_state + 0x7fe4);
     ESP = ldl_phys(sm_state + 0x7fe0);
-    EBX = ldl_phys(sm_state + 0x7fdc);
+    env->regs[R_EBX] = ldl_phys(sm_state + 0x7fdc);
     EDX = ldl_phys(sm_state + 0x7fd8);
     ECX = ldl_phys(sm_state + 0x7fd4);
     env->regs[R_EAX] = ldl_phys(sm_state + 0x7fd0);
