diff --git a/cfg/posix.cfg b/cfg/posix.cfg
index 34c94b578..969db0bec 100644
--- a/cfg/posix.cfg
+++ b/cfg/posix.cfg
@@ -1,5 +1,28 @@
 <?xml version="1.0"?>
 <def format="1">
+  <!-- int flock(int fd, int operation); -->
+  <function name="flock">
+    <noreturn>false</noreturn>
+    <arg nr="1">
+      <not-uninit/>
+    </arg>
+    <arg nr="2">
+      <not-uninit/>
+    </arg>
+    <leak-ignore/>
+  </function>
+  <!-- int open(const char *pathname, int flags) -->
+  <function name="open">
+    <use-retval/>
+    <noreturn>false</noreturn>
+    <arg nr="1">
+      <not-null/>
+      <not-uninit/>
+    </arg>
+    <arg nr="2">
+      <not-uninit/>
+    </arg>
+  </function>
   <!-- unsigned int sleep(unsigned int seconds); -->
   <function name="sleep">
     <noreturn>false</noreturn>