diff --git a/arch_init.c b/arch_init.c
index 988adcae07cef66b234c99441699fe51b7210c05..a9e8b7442be112afeebc6f32b92d471048a26a84 100644
--- a/arch_init.c
+++ b/arch_init.c
@@ -100,6 +100,10 @@ const uint32_t arch_type = QEMU_ARCH;
 #define VECTYPE        vector unsigned char
 #define SPLAT(p)       vec_splat(vec_ld(0, p), 0)
 #define ALL_EQ(v1, v2) vec_all_eq(v1, v2)
+/* altivec.h may redefine the bool macro as vector type.
+ * Reset it to POSIX semantics. */
+#undef bool
+#define bool _Bool
 #elif defined __SSE2__
 #include <emmintrin.h>
 #define VECTYPE        __m128i