diff --git a/userspace/libsinsp/threadinfo.h b/userspace/libsinsp/threadinfo.h
index 4da7e655ad..4677525b2b 100644
--- a/userspace/libsinsp/threadinfo.h
+++ b/userspace/libsinsp/threadinfo.h
@@ -198,7 +198,7 @@ class SINSP_PUBLIC sinsp_threadinfo : public libsinsp::state::table_entry
 	*/
 	inline bool is_in_pid_namespace() const
 	{
-		return (m_flags & PPM_CL_CHILD_IN_PIDNS || m_tid != m_vtid);
+		return (m_flags & PPM_CL_CHILD_IN_PIDNS || (m_tid != m_vtid && m_vtid >= 0));
 	}
 
 	/*!