diff --git a/proj/server/src/intercept/__init__.py b/proj/server/src/intercept/__init__.py
index 8664ca5..d21ff08 100644
--- a/proj/server/src/intercept/__init__.py
+++ b/proj/server/src/intercept/__init__.py
@@ -263,7 +263,7 @@ class Parser:
                     idx += 1
                 value = int(value, 0) if value != '(nil)' else 0
                 return PointerTo(val, value), idx
-            m = re.match(r'[A-Z0-9_]+', argument[idx:])
+            m = re.match(r'[A-Z0-9_]+|\?', argument[idx:])
             if m is not None:
                 value = m.group(0)
                 idx += len(value)
@@ -302,6 +302,8 @@ class Parser:
         self.pid, self.tid = int(pid), int(tid)
         if len(self.stack) == 0:
             self.stack[(self.pid, self.tid)] = []
+        elif (self.pid, self.tid) not in self.stack:
+            self.stack[(self.pid, self.tid)] = []
         if not data.startswith(b'return ') and not data == b'return':
             call = data.decode('utf-8')
             #print(f'[{self.pid}][{self.tid}] {call}')
diff --git a/proj/server/src/test-return-values b/proj/server/src/test-return-values
index 8625585..33415d2 100755
--- a/proj/server/src/test-return-values
+++ b/proj/server/src/test-return-values
@@ -102,7 +102,7 @@ def main() -> None:
                 entry[ret] = set()
             entry[ret].add(tuple(c for c in iter_tree_ok(child)))
 
-    allowed_cleanup_functions = ['malloc', 'free', 'freeaddrinfo', 'close', 'exit']
+    allowed_cleanup_functions = ['malloc', 'free', 'freeaddrinfo', 'close', 'exit', 'sigaction']
     for call, errors in calls.items():
         if len(errors) <= 1:
             continue