diff --git a/cfg/posix.cfg b/cfg/posix.cfg
index fac7a8744..ed9c02fd5 100644
--- a/cfg/posix.cfg
+++ b/cfg/posix.cfg
@@ -3512,7 +3512,7 @@ The function 'mktemp' is considered to be dangerous due to race conditions and s
     <arg nr="4" direction="in">
       <not-uninit/>
       <not-bool/>
-      <valid>:1</valid>
+      <valid>1:</valid>
     </arg>
     <arg nr="5" direction="in">
       <not-uninit/>
@@ -3539,13 +3539,41 @@ The function 'mktemp' is considered to be dangerous due to race conditions and s
     <arg nr="4" direction="in">
       <not-uninit/>
       <not-bool/>
-      <valid>:1</valid>
+      <valid>1:</valid>
     </arg>
     <arg nr="5" direction="in">
       <not-uninit/>
       <not-null/>
     </arg>
   </function>
+  <!-- https://man7.org/linux/man-pages/man3/mbsnrtowcs.3.html -->
+  <!-- size_t mbsnrtowcs(wchar_t *restrict dest, const char **restrict src, size_t nms, size_t len, mbstate_t *restrict ps) -->
+  <function name="mbsnrtowcs">
+    <returnValue type="size_t"/>
+    <use-retval/>
+    <noreturn>false</noreturn>
+    <arg nr="1" direction="out">
+      <not-null/>
+    </arg>
+    <arg nr="2" direction="in">
+      <not-uninit/>
+      <not-null/>
+      <minsize type="argvalue" arg="3"/>
+    </arg>
+    <arg nr="3" direction="in">
+      <not-uninit/>
+      <not-null/>
+      <valid>0:</valid>
+    </arg>
+    <arg nr="4" direction="in">
+      <not-uninit/>
+      <not-bool/>
+      <valid>0:</valid>
+    </arg>
+    <arg nr="5" direction="in">
+      <not-null/>
+    </arg>
+  </function>
   <!-- https://pubs.opengroup.org/onlinepubs/9699919799/functions/regcomp.html -->
   <!-- int regcomp(regex_t *restrict preg, const char *restrict pattern, int cflags); -->
   <function name="regcomp">