diff --git a/cfg/posix.cfg b/cfg/posix.cfg
index 20f224947..78e6452b1 100644
--- a/cfg/posix.cfg
+++ b/cfg/posix.cfg
@@ -16,7 +16,7 @@
   <function name="mkdir">
 	  <noreturn>false</noreturn>
 	  <arg nr="1"><not-uninit/><not-null/></arg>
-	  <arg nr="2"><not-uninit/><not-null/></arg>
+	  <arg nr="2"><not-uninit/></arg>
 	  <leak-ignore/>
  </function>
   <function name="rmdir"> <noreturn>false</noreturn> <arg nr="1"><not-uninit/><not-null/></arg> <leak-ignore/> </function>
diff --git a/test/testnullpointer.cpp b/test/testnullpointer.cpp
index 8f5f74716..56692c523 100644
--- a/test/testnullpointer.cpp
+++ b/test/testnullpointer.cpp
@@ -2605,6 +2605,15 @@ private:
 
         check("void f(){ isatty (0);}");
         ASSERT_EQUALS("",errout.str());
+
+        check("void f(char *p){ mkdir (p, 0);}");
+        ASSERT_EQUALS("",errout.str());
+
+        check("void f(char *p){ int i = 0; mkdir (p, i);}");
+        ASSERT_EQUALS("",errout.str());
+
+        check("void f(char *p){ mkdir (p, *0);}");
+        ASSERT_EQUALS("[test.cpp:1]: (error) Null pointer dereference\n",errout.str());
     }
 };