diff --git a/cfg/posix.cfg b/cfg/posix.cfg
index 47fbe9cd1..7bd579621 100644
--- a/cfg/posix.cfg
+++ b/cfg/posix.cfg
@@ -3892,6 +3892,7 @@ The function 'mktemp' is considered to be dangerous due to race conditions and s
     <arg nr="1" direction="in">
       <not-uninit/>
       <not-bool/>
+      <valid>0:</valid>
     </arg>
     <arg nr="2" direction="in">
       <not-null/>
@@ -3900,6 +3901,7 @@ The function 'mktemp' is considered to be dangerous due to race conditions and s
     <arg nr="3" direction="in">
       <not-uninit/>
       <not-bool/>
+      <valid>0:</valid>
     </arg>
     <arg nr="4" direction="in">
       <not-null/>