diff --git a/src/input/input_event.cc b/src/input/input_event.cc
index 530e0ca4..b6126540 100644
--- a/src/input/input_event.cc
+++ b/src/input/input_event.cc
@@ -13,7 +13,6 @@ void
 InputEvent::insert() {
   torrent::this_thread::poll()->open(this);
   torrent::this_thread::poll()->insert_read(this);
-  torrent::this_thread::poll()->insert_error(this);
 }
 
 void
diff --git a/src/input/input_event.h b/src/input/input_event.h
index 945605d9..b98a1d29 100644
--- a/src/input/input_event.h
+++ b/src/input/input_event.h
@@ -11,7 +11,7 @@ class InputEvent : public torrent::Event {
 public:
   typedef std::function<void (int)> slot_int;
 
-  InputEvent(int fd) { m_fileDesc = fd; }
+  InputEvent(int fd) { set_file_descriptor(fd); }
 
   const char*         type_name() const override { return "input"; }
 
diff --git a/src/rpc/exec_file.cc b/src/rpc/exec_file.cc
index d3733885..51f77d37 100644
--- a/src/rpc/exec_file.cc
+++ b/src/rpc/exec_file.cc
@@ -1,5 +1,6 @@
 #include "config.h"
 
+#include <cassert>
 #include <cerrno>
 #include <cstring>
 #include <fcntl.h>
@@ -24,6 +25,8 @@ namespace rpc {
 
 int
 ExecFile::execute(const char* file, char* const* argv, int flags) {
+  assert(!((flags & flag_capture) && (flags & flag_background)));
+
   // Write the executed command and its parameters to the log fd.
   [[maybe_unused]] int result;
 
diff --git a/src/rpc/scgi.cc b/src/rpc/scgi.cc
index 8fc90d11..4f665547 100644
--- a/src/rpc/scgi.cc
+++ b/src/rpc/scgi.cc
@@ -111,7 +111,6 @@ SCgi::activate() {
 
   torrent::this_thread::poll()->open(this);
   torrent::this_thread::poll()->insert_read(this);
-  torrent::this_thread::poll()->insert_error(this);
 }
 
 // TODO: This should close the fd to avoid reuse.
diff --git a/src/rpc/scgi_task.cc b/src/rpc/scgi_task.cc
index f940f95c..f9a05882 100644
--- a/src/rpc/scgi_task.cc
+++ b/src/rpc/scgi_task.cc
@@ -27,7 +27,7 @@ namespace rpc {
 SCgiTask::SCgiTask()
   : m_callback_id(torrent::system::make_callback_id()) {
 
-  set_file_descriptor(-1);
+  reset_file_descriptor();
 }
 
 void
@@ -49,7 +49,6 @@ SCgiTask::open(SCgi* parent, int fd) {
 
   torrent::this_thread::poll()->open(this);
   torrent::this_thread::poll()->insert_read(this);
-  torrent::this_thread::poll()->insert_error(this);
 
   auto lock = std::lock_guard<std::mutex>(m_result_mutex);
 
@@ -65,7 +64,7 @@ SCgiTask::cancel_open() {
   torrent::this_thread::poll()->remove_and_close(this);
 
   torrent::fd_close(file_descriptor());
-  set_file_descriptor(-1);
+  reset_file_descriptor();
 };
 
 void
@@ -79,7 +78,7 @@ SCgiTask::close() {
       torrent::this_thread::poll()->remove_and_close(this);
 
       torrent::fd_close(file_descriptor());
-      set_file_descriptor(-1);
+      reset_file_descriptor();
     });
 
   // The callbacks are guaranteed to be finished/canceled at this point.
@@ -98,7 +97,7 @@ SCgiTask::event_read() {
   if (read_length <= 0)
     throw torrent::internal_error("SCgiTask::event_read() no space in buffer for event_read.");
 
-  int bytes = ::recv(m_fileDesc, m_buffer.data() + m_position, read_length, 0);
+  int bytes = ::recv(file_descriptor(), m_buffer.data() + m_position, read_length, 0);
 
   if (bytes <= 0) {
     if (bytes == 0 || !(errno == EAGAIN || errno == EINTR))
@@ -181,7 +180,7 @@ event_read_failed:
 
 void
 SCgiTask::event_write() {
-  int bytes = ::send(m_fileDesc, m_buffer.data() + m_position, m_buffer.size() - m_position, 0);
+  int bytes = ::send(file_descriptor(), m_buffer.data() + m_position, m_buffer.size() - m_position, 0);
 
   if (bytes == -1) {
     if (!(errno == EAGAIN || errno == EINTR))
diff --git a/src/rpc/scgi_task.h b/src/rpc/scgi_task.h
index 1b3961b1..8cb30184 100644
--- a/src/rpc/scgi_task.h
+++ b/src/rpc/scgi_task.h
@@ -22,8 +22,8 @@ public:
 
   const char*         type_name() const override { return "scgi-task"; }
 
-  bool                is_open() const      { return m_fileDesc != -1; }
-  bool                is_available() const { return m_fileDesc == -1; }
+  bool                is_open() const      { return file_descriptor() != -1; }
+  bool                is_available() const { return file_descriptor() == -1; }
 
   void                open(SCgi* parent, int fd);
   void                cancel_open();