diff --git a/cfg/posix.cfg b/cfg/posix.cfg
index 6483054f9..5f7edd788 100644
--- a/cfg/posix.cfg
+++ b/cfg/posix.cfg
@@ -1685,7 +1685,9 @@ The function 'mktemp' is considered to be dangerous due to race conditions and s
     <returnValue type="int"/>
     <noreturn>false</noreturn>
     <arg nr="1" direction="out">
+      <not-null/>
       <not-bool/>
+      <minsize type="value" value="2"/>
     </arg>
   </function>
   <!-- int pselect(int nfds, fd_set *restrict readfds,