diff --git a/include/asm-mips/system.h b/include/asm-mips/system.h
index be64fc5..46bdb3f 100644
--- a/include/asm-mips/system.h
+++ b/include/asm-mips/system.h
@@ -56,7 +56,7 @@
 } while(0)
 
 #else
-#define __mips_mt_fpaff_switch_to(prev) do { (prev); } while (0)
+#define __mips_mt_fpaff_switch_to(prev) do { (void) (prev); } while (0)
 #endif
 
 #define switch_to(prev,next,last)					\