diff --git a/SheepShaver/src/Unix/configure.in b/SheepShaver/src/Unix/configure.in
index 2c16eefb..0be17879 100644
--- a/SheepShaver/src/Unix/configure.in
+++ b/SheepShaver/src/Unix/configure.in
@@ -183,9 +183,6 @@ AC_HEADER_SYS_WAIT
 AC_CHECK_HEADERS(mach/vm_map.h mach/mach_init.h sys/mman.h)
 AC_CHECK_HEADERS(sys/time.h sys/times.h)
 AC_CHECK_HEADERS(unistd.h fcntl.h byteswap.h)
-AC_CHECK_HEADERS(mmintrin.h, [have_mmintrin_h=yes])
-AC_CHECK_HEADERS(xmmintrin.h, [have_xmmintrin_h=yes])
-AC_CHECK_HEADERS(emmintrin.h, [have_emmintrin_h=yes])
 
 dnl Checks for typedefs, structures, and compiler characteristics.
 AC_C_BIGENDIAN
@@ -728,15 +725,17 @@ if [[ "x$EMULATED_PPC" = "xyes" ]]; then
         else
           DYNGEN_OP_FLAGS="$DYNGEN_OP_FLAGS -malign-functions=0"
         fi
-        if [[ "x$have_mmintrin_h" = "xyes" ]]; then
-          DYNGEN_OP_FLAGS="$DYNGEN_OP_FLAGS -mmmx"
-        fi
-        if [[ "x$have_xmmintrin_h" = "xyes" ]]; then
-          DYNGEN_OP_FLAGS="$DYNGEN_OP_FLAGS -msse"
-        fi
-        if [[ "x$have_emmintrin_h" = "xyes" ]]; then
-          DYNGEN_OP_FLAGS="$DYNGEN_OP_FLAGS -msse2"
-        fi
+        saved_CPPFLAGS=$CPPFLAGS
+        CPPFLAGS="$CPPFLAGS -mmmx"
+        AC_CHECK_HEADERS(mmintrin.h,  [DYNGEN_OP_FLAGS="$DYNGEN_OP_FLAGS -mmmx"])
+        CPPFLAGS="$CPPFLAGS -msse"
+        AC_CHECK_HEADERS(xmmintrin.h, [DYNGEN_OP_FLAGS="$DYNGEN_OP_FLAGS -msse"])
+        CPPFLAGS="$CPPFLAGS -msse2"
+        AC_CHECK_HEADERS(emmintrin.h, [DYNGEN_OP_FLAGS="$DYNGEN_OP_FLAGS -msse2"])
+        CPPFLAGS=$saved_CPPFLAGS
+        ;;
+      x86_64)
+        AC_CHECK_HEADERS(mmintrin.h xmmintrin.h emmintrin.h)
         ;;
       esac
       DYNGEN_OP_FLAGS="$DYNGEN_OP_FLAGS -finline-limit=10000"
diff --git a/SheepShaver/src/kpx_cpu/src/cpu/ppc/ppc-dyngen-ops.cpp b/SheepShaver/src/kpx_cpu/src/cpu/ppc/ppc-dyngen-ops.cpp
index 57e51d81..5555d435 100644
--- a/SheepShaver/src/kpx_cpu/src/cpu/ppc/ppc-dyngen-ops.cpp
+++ b/SheepShaver/src/kpx_cpu/src/cpu/ppc/ppc-dyngen-ops.cpp
@@ -1334,37 +1334,43 @@ void op_store_vect_VD_T0(void)
  *		Vector operations helpers
  **/
 
-struct VNONE {
+#define VNONE op_VNONE
+struct op_VNONE {
 	typedef null_operand type;
 	static inline uint32 get(powerpc_vr const & v, int i) { return 0; }
 	static inline void set(powerpc_vr const & v, int i, uint32) { }
 };
 
-struct V16QI {
+#define V16QI op_V16QI
+struct op_V16QI {
 	typedef uint8 type;
 	static inline type get(powerpc_vr const & v, int i) { return v.b[i]; }
 	static inline void set(powerpc_vr & v, int i, type x) { v.b[i] = x; }
 };
 
-struct V8HI {
+#define V8HI op_V8HI
+struct op_V8HI {
 	typedef uint16 type;
 	static inline type get(powerpc_vr const & v, int i) { return v.h[i]; }
 	static inline void set(powerpc_vr & v, int i, type x) { v.h[i] = x; }
 };
 
-struct V4SI {
+#define V4SI op_V4SI
+struct op_V4SI {
 	typedef uint32 type;
 	static inline type get(powerpc_vr const & v, int i) { return v.w[i]; }
 	static inline void set(powerpc_vr & v, int i, type x) { v.w[i] = x; }
 };
 
-struct V2DI {
+#define V2DI op_V2DI
+struct op_V2DI {
 	typedef uint64 type;
 	static inline type get(powerpc_vr const & v, int i) { return v.j[i]; }
 	static inline void set(powerpc_vr & v, int i, type x) { v.j[i] = x; }
 };
 
-struct V4SF {
+#define V4SF op_V4SF
+struct op_V4SF {
 	typedef float type;
 	static inline type get(powerpc_vr const & v, int i) { return v.f[i]; }
 	static inline void set(powerpc_vr & v, int i, type x) { v.f[i] = x; }
@@ -1485,6 +1491,13 @@ void op_record_cr6_VD(void)
 	dyngen_barrier();
 }
 
+#undef VNONE
+#undef V16QI
+#undef V8HI
+#undef V4SI
+#undef V2DI
+#undef V4SF
+
 /**
  *		SSE optimizations
  **/