diff --git a/include/reactor-uc/connection.h b/include/reactor-uc/connection.h
index 315030ec..01172afc 100644
--- a/include/reactor-uc/connection.h
+++ b/include/reactor-uc/connection.h
@@ -14,6 +14,7 @@ typedef struct PhysicalConnection PhysicalConnection;
 typedef struct DelayedConnection DelayedConnection;
 typedef struct Port Port;
 typedef struct Output Output;
+typedef struct ConnectionList ConnectionList;
 
 struct Connection {
   Trigger super;
@@ -30,6 +31,11 @@ void Connection_ctor(Connection *self, TriggerType type, Reactor *parent, Port *
                      EventPayloadPool *payload_pool, void (*prepare)(Trigger *, Event *), void (*cleanup)(Trigger *),
                      void (*trigger_downstreams)(Connection *, const void *, size_t));
 
+struct ConnectionList {
+  Connection **connections;
+  size_t connections_size;
+};
+
 struct LogicalConnection {
   Connection super;
 };
diff --git a/include/reactor-uc/macros.h b/include/reactor-uc/macros.h
index c7ea3648..623d4a5b 100644
--- a/include/reactor-uc/macros.h
+++ b/include/reactor-uc/macros.h
@@ -104,9 +104,9 @@
     Connection *conns_out[NumConnsOut];                                                                                \
   } PortName;
 
-#define DEFINE_OUTPUT_PORT_CTOR(PortName, SourceSize, NumConnsOut)                                                     \
-  void PortName##_ctor(PortName *self, Reactor *parent) {                                                              \
-    Output_ctor(&self->super, parent, self->sources, SourceSize, (Connection **)&self->conns_out, NumConnsOut);        \
+#define DEFINE_OUTPUT_PORT_CTOR(PortName, SourceSize)                                                                  \
+  void PortName##_ctor(PortName *self, Reactor *parent, Connection **conn_out, size_t conn_num) {                      \
+    Output_ctor(&self->super, parent, self->sources, SourceSize, conn_out, conn_num);                                  \
   }
 
 #define DEFINE_INPUT_PORT_STRUCT(PortName, EffectSize, BufferType, NumConnsOut)                                        \
diff --git a/test/unit/delayed_conn_test.c b/test/unit/delayed_conn_test.c
index d66b7d92..7e47f3db 100644
--- a/test/unit/delayed_conn_test.c
+++ b/test/unit/delayed_conn_test.c
@@ -6,7 +6,7 @@ DEFINE_TIMER_STRUCT(Timer1, 1)
 DEFINE_TIMER_CTOR_FIXED(Timer1, 1, 0, MSEC(10))
 DEFINE_REACTION_STRUCT(Sender, 0, 0);
 DEFINE_OUTPUT_PORT_STRUCT(Out, 1, 1)
-DEFINE_OUTPUT_PORT_CTOR(Out, 1, 1)
+DEFINE_OUTPUT_PORT_CTOR(Out, 1)
 
 typedef struct {
   Reactor super;
@@ -27,13 +27,13 @@ DEFINE_REACTION_BODY(Sender, 0) {
 }
 DEFINE_REACTION_CTOR(Sender, 0);
 
-void Sender_ctor(Sender *self, Reactor *parent, Environment *env) {
+void Sender_ctor(Sender *self, Reactor *parent, Environment *env, Connection** conn_out, size_t conn_out_num) {
   self->_reactions[0] = (Reaction *)&self->reaction;
   self->_triggers[0] = (Trigger *)&self->timer;
   Reactor_ctor(&self->super, "Sender", env, parent, NULL, 0, self->_reactions, 1, self->_triggers, 1);
   Sender_Reaction0_ctor(&self->reaction, &self->super);
   Timer1_ctor(&self->timer, &self->super);
-  Out_ctor(&self->out, &self->super);
+  Out_ctor(&self->out, &self->super, conn_out, conn_out_num);
 
   TIMER_REGISTER_EFFECT(self->timer, self->reaction);
 
@@ -87,11 +87,12 @@ typedef struct {
   Conn1 conn;
 
   Reactor *_children[2];
+  Connection *_conn_sender_out[1];
 } Main;
 
 void Main_ctor(Main *self, Environment *env) {
   self->_children[0] = &self->sender.super;
-  Sender_ctor(&self->sender, &self->super, env);
+  Sender_ctor(&self->sender, &self->super, env, self->_conn_sender_out, 1);
 
   self->_children[1] = &self->receiver.super;
   Receiver_ctor(&self->receiver, &self->super, env);
diff --git a/test/unit/port_test.c b/test/unit/port_test.c
index 979be3a4..5c41702d 100644
--- a/test/unit/port_test.c
+++ b/test/unit/port_test.c
@@ -6,7 +6,7 @@ DEFINE_TIMER_STRUCT(Timer1, 1)
 DEFINE_TIMER_CTOR_FIXED(Timer1, 1, 0, SEC(1))
 DEFINE_REACTION_STRUCT(Sender, 0, 0)
 DEFINE_OUTPUT_PORT_STRUCT(Out, 1, 1)
-DEFINE_OUTPUT_PORT_CTOR(Out, 1, 1)
+DEFINE_OUTPUT_PORT_CTOR(Out, 1)
 
 typedef struct {
   Reactor super;
@@ -27,13 +27,13 @@ DEFINE_REACTION_BODY(Sender, 0) {
 }
 DEFINE_REACTION_CTOR(Sender, 0)
 
-void Sender_ctor(Sender *self, Reactor *parent, Environment *env) {
+void Sender_ctor(Sender *self, Reactor *parent, Environment *env, Connection** conn_out, size_t conn_num) {
   self->_reactions[0] = (Reaction *)&self->reaction;
   self->_triggers[0] = (Trigger *)&self->timer;
   Reactor_ctor(&self->super, "Sender", env, parent, NULL, 0, self->_reactions, 1, self->_triggers, 1);
   Sender_Reaction0_ctor(&self->reaction, &self->super);
   Timer1_ctor(&self->timer, &self->super);
-  Out_ctor(&self->out, &self->super);
+  Out_ctor(&self->out, &self->super, conn_out, conn_num);
   TIMER_REGISTER_EFFECT(self->timer, self->reaction);
   OUTPUT_REGISTER_SOURCE(self->out, self->reaction);
 }
@@ -85,11 +85,12 @@ typedef struct {
   Conn1 conn;
 
   Reactor *_children[2];
+  Connection *_conn_sender_out[1];
 } Main;
 
 void Main_ctor(Main *self, Environment *env) {
   self->_children[0] = &self->sender.super;
-  Sender_ctor(&self->sender, &self->super, env);
+  Sender_ctor(&self->sender, &self->super, env, self->_conn_sender_out, 1);
 
   self->_children[1] = &self->receiver.super;
   Receiver_ctor(&self->receiver, &self->super, env);