diff --git a/ppc-dis.c b/ppc-dis.c
index ca5765a60e..ffdbec18db 100644
--- a/ppc-dis.c
+++ b/ppc-dis.c
@@ -572,6 +572,7 @@ const struct powerpc_operand powerpc_operands[] =
 
   /* The DS field in a DS form instruction.  This is like D, but the
      lower two bits are forced to zero.  */
+#undef DS
 #define DS DQ + 1
   { 0xfffc, 0, NULL, NULL,
     PPC_OPERAND_PARENS | PPC_OPERAND_SIGNED | PPC_OPERAND_DS },
diff --git a/target-i386/exec.h b/target-i386/exec.h
index c59c4e872b..864d030986 100644
--- a/target-i386/exec.h
+++ b/target-i386/exec.h
@@ -33,14 +33,23 @@ register struct CPUX86State *env asm(AREG0);
 #include "qemu-common.h"
 #include "qemu-log.h"
 
+#undef EAX
 #define EAX (env->regs[R_EAX])
+#undef ECX
 #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
 #define EBP (env->regs[R_EBP])
+#undef ESI
 #define ESI (env->regs[R_ESI])
+#undef EDI
 #define EDI (env->regs[R_EDI])
+#undef EIP
 #define EIP (env->eip)
 #define DF  (env->df)