diff --git a/cfg/posix.cfg b/cfg/posix.cfg
index 9521a08b4..d14413c98 100644
--- a/cfg/posix.cfg
+++ b/cfg/posix.cfg
@@ -2326,6 +2326,7 @@ The function 'mktemp' is considered to be dangerous due to race conditions and s
       <valid>0:</valid>
     </arg>
     <arg nr="2" direction="in">
+      <not-null/>
       <minsize type="argvalue" arg="3"/>
     </arg>
     <arg nr="3" direction="in">
@@ -2335,9 +2336,13 @@ The function 'mktemp' is considered to be dangerous due to race conditions and s
     <arg nr="4" direction="in">
       <not-uninit/>
     </arg>
-    <arg nr="5" direction="in"/>
+    <arg nr="5" direction="in">
+      <not-uninit/>
+    </arg>
     <arg nr="6" direction="in">
       <not-bool/>
+      <not-uninit/>
+      <valid>0:</valid>
     </arg>
   </function>
   <!-- ssize_t sendmsg(int sockfd, const struct msghdr *msg, int flags); -->
diff --git a/test/cfg/posix.c b/test/cfg/posix.c
index df1164cb1..53699eb52 100644
--- a/test/cfg/posix.c
+++ b/test/cfg/posix.c
@@ -601,6 +601,16 @@ void validCode(va_list valist_arg1, va_list valist_arg2)
     }
 }
 
+ssize_t nullPointer_sendto(int socket, const void *message, size_t length,
+                           int flags, const struct sockaddr *dest_addr,
+                           socklen_t dest_len)
+{
+    // cppcheck-suppress nullPointer
+    (void) sendto(socket, NULL, length, flags, dest_addr, dest_len);
+    (void) sendto(socket, message, length, flags, NULL, dest_len);
+    return sendto(socket, message, length, flags, dest_addr, dest_len);
+}
+
 void bufferAccessOutOfBounds(int fd)
 {
     char a[5];