diff --git a/src/event/MultiSocketMonitor.hxx b/src/event/MultiSocketMonitor.hxx
index 781fdeca6..50be18070 100644
--- a/src/event/MultiSocketMonitor.hxx
+++ b/src/event/MultiSocketMonitor.hxx
@@ -101,7 +101,10 @@ public:
 	}
 
 protected:
-	virtual void PrepareSockets(gcc_unused gint *timeout_r) {}
+	/**
+	 * @return timeout [ms] or -1 for no timeout
+	 */
+	virtual int PrepareSockets() = 0;
 	virtual bool CheckSockets() const { return false; }
 	virtual void DispatchSockets() = 0;
 
@@ -114,7 +117,7 @@ public:
 
 private:
 	bool Prepare(gint *timeout_r) {
-		PrepareSockets(timeout_r);
+		*timeout_r = PrepareSockets();
 		return false;
 	}
 
diff --git a/src/input/CurlInputPlugin.cxx b/src/input/CurlInputPlugin.cxx
index 8e29e47c7..56a42709a 100644
--- a/src/input/CurlInputPlugin.cxx
+++ b/src/input/CurlInputPlugin.cxx
@@ -204,7 +204,7 @@ public:
 private:
 	void UpdateSockets();
 
-	virtual void PrepareSockets(gcc_unused gint *timeout_r) override;
+	virtual int PrepareSockets() override;
 	virtual bool CheckSockets() const override;
 	virtual void DispatchSockets() override;
 };
@@ -536,8 +536,8 @@ input_curl_perform(void)
 	return true;
 }
 
-void
-CurlSockets::PrepareSockets(gint *timeout_r)
+int
+CurlSockets::PrepareSockets()
 {
 	UpdateSockets();
 
@@ -556,12 +556,13 @@ CurlSockets::PrepareSockets(gint *timeout_r)
 			   Let's use a lower limit of 10ms. */
 			timeout2 = 10;
 
-		*timeout_r = timeout2;
-
 		have_timeout = timeout2 >= 0;
-	} else
+		return timeout2;
+	} else {
 		g_warning("curl_multi_timeout() failed: %s\n",
 			  curl_multi_strerror(mcode));
+		return -1;
+	}
 }
 
 bool
diff --git a/src/mixer/AlsaMixerPlugin.cxx b/src/mixer/AlsaMixerPlugin.cxx
index 5ab19a8d6..5191826c5 100644
--- a/src/mixer/AlsaMixerPlugin.cxx
+++ b/src/mixer/AlsaMixerPlugin.cxx
@@ -44,7 +44,7 @@ public:
 		:MultiSocketMonitor(_loop), mixer(_mixer) {}
 
 private:
-	virtual void PrepareSockets(gcc_unused gint *timeout_r) override;
+	virtual int PrepareSockets() override;
 	virtual void DispatchSockets() override;
 };
 
@@ -83,8 +83,8 @@ alsa_mixer_quark(void)
 	return g_quark_from_static_string("alsa_mixer");
 }
 
-void
-AlsaMixerMonitor::PrepareSockets(gcc_unused gint *timeout_r)
+int
+AlsaMixerMonitor::PrepareSockets()
 {
 	int count = snd_mixer_poll_descriptors_count(mixer);
 	if (count < 0)
@@ -113,6 +113,8 @@ AlsaMixerMonitor::PrepareSockets(gcc_unused gint *timeout_r)
 	for (auto i = pfds; i != end; ++i)
 		if (i->events != 0)
 			AddSocket(i->fd, i->events);
+
+	return -1;
 }
 
 void