Eliminated warnings.

diff --git a/dlls/msacm32/internal.c b/dlls/msacm32/internal.c
index ca9f702..e1ad05f 100644
--- a/dlls/msacm32/internal.c
+++ b/dlls/msacm32/internal.c
@@ -4,6 +4,8 @@
  *      Copyright 1998  Patrik Stridvall
  */
 
+#include <string.h>
+
 #include "winbase.h"
 #include "winuser.h"
 #include "winerror.h"