diff --git a/sys/powerpc/include/cpufunc.h b/sys/powerpc/include/cpufunc.h
index 84be33d7ce0..f02ff3bd55a 100644
--- a/sys/powerpc/include/cpufunc.h
+++ b/sys/powerpc/include/cpufunc.h
@@ -65,7 +65,7 @@ static __inline void
 mtmsr(register_t value)
 {
 
-	__asm __volatile ("mtmsr %0" :: "r"(value));
+	__asm __volatile ("mtmsr %0; isync" :: "r"(value));
 }
 
 static __inline register_t