diff --git a/e_os.h b/e_os.h
index 95590a7cb2606be26e16638446e30de983ddae2c..948a8bfd7e1b664c5af9fe95b44ee5f7090d9927 100644
--- a/e_os.h
+++ b/e_os.h
@@ -404,7 +404,7 @@ extern HINSTANCE _hInstance;
 #endif
 
 #if defined(sun) && !defined(__svr4__) && !defined(__SVR4)
-#define memmove(s1,s2,b) bcopy((s2),(s1),(n))
+#define memmove(s1,s2,n) bcopy((s2),(s1),(n))
 #endif
 
 /***********************************************/