diff --git a/cfg/posix.cfg b/cfg/posix.cfg
index 98764ead0..9e1c39099 100644
--- a/cfg/posix.cfg
+++ b/cfg/posix.cfg
@@ -40,9 +40,8 @@
       <not-bool/>
       <valid>0:</valid>
     </arg>
-    <arg nr="5" direction="in">
+    <arg nr="5" direction="inout">
       <not-uninit/>
-      <not-null/>
     </arg>
   </function>
   <!-- https://man7.org/linux/man-pages/man3/aio_read.3.html -->
diff --git a/test/cfg/posix.c b/test/cfg/posix.c
index 6134b57ff..d32929a54 100644
--- a/test/cfg/posix.c
+++ b/test/cfg/posix.c
@@ -53,7 +53,7 @@ size_t nullPointer_wcsnrtombs(char *restrict dest, const wchar_t **restrict src,
     (void)wcsnrtombs(NULL,src,nwc,len,ps);
     // cppcheck-suppress nullPointer
     (void)wcsnrtombs(dest,NULL,nwc,len,ps);
-    // cppcheck-suppress nullPointer
+    // It is allowed to set the last arg to NULL
     (void)wcsnrtombs(dest,src,nwc,len,NULL);
     return wcsnrtombs(dest,src,nwc,len,ps);
 }