diff --git a/cfg/posix.cfg b/cfg/posix.cfg
index adcdb2a2b..cc8062add 100644
--- a/cfg/posix.cfg
+++ b/cfg/posix.cfg
@@ -28,6 +28,7 @@
 	  <leak-ignore/>
  </function>
   <function name="rename"> <noreturn>false</noreturn> <arg nr="1"><not-uninit/><not-null/></arg> <leak-ignore/> </function>
+  <function name="isatty"> <noreturn>false</noreturn> <arg nr="1"><not-uninit/><not-null/></arg> <leak-ignore/> </function>
   <resource>
     <dealloc>close</dealloc>
     <alloc init="true">open</alloc>