diff --git a/newlib/libc/machine/arc/memset-archs.S b/newlib/libc/machine/arc/memset-archs.S
index 188b5c490..dc912aa77 100644
--- a/newlib/libc/machine/arc/memset-archs.S
+++ b/newlib/libc/machine/arc/memset-archs.S
@@ -37,6 +37,8 @@
 
 #ifdef __ARCHS__
 
+#define USE_PREFETCH
+
 #ifdef USE_PREFETCH
 #define PREWRITE(A,B)	prefetchw [(A),(B)]
 #else