diff --git a/cfg/posix.cfg b/cfg/posix.cfg
index d6ea183f4..cc08f22a5 100644
--- a/cfg/posix.cfg
+++ b/cfg/posix.cfg
@@ -2570,6 +2570,7 @@ The function 'mktemp' is considered to be dangerous due to race conditions and s
     <arg nr="1">
       <not-null/>
       <not-uninit/>
+      <minsize type="argvalue" arg="3"/>
     </arg>
     <arg nr="2">
       <not-null/>