diff --git a/include/haproxy/stream_interface.h b/include/haproxy/stream_interface.h
index 6c74007a7..3239c059d 100644
--- a/include/haproxy/stream_interface.h
+++ b/include/haproxy/stream_interface.h
@@ -313,6 +313,24 @@ static inline void si_update(struct stream_interface *si)
 	si_update_tx(si);
 }
 
+/* The stream interface is only responsible for the connection during the early
+ * states, before plugging a mux. Thus it should only care about CO_FL_ERROR
+ * before CS_ST_EST, and after that it must absolutely ignore it since the mux
+ * may hold pending data. This function returns true if such an error was
+ * reported. Both the CS and the CONN must be valid.
+ */
+static inline int si_is_conn_error(const struct stream_interface *si)
+{
+	struct connection *conn;
+
+	if (si->cs->state >= CS_ST_EST)
+		return 0;
+
+	conn = __cs_conn(si->cs);
+	BUG_ON(!conn);
+	return !!(conn->flags & CO_FL_ERROR);
+}
+
 #endif /* _HAPROXY_STREAM_INTERFACE_H */
 
 /*
diff --git a/src/stream_interface.c b/src/stream_interface.c
index ddeab7cc6..f2dfbcdb4 100644
--- a/src/stream_interface.c
+++ b/src/stream_interface.c
@@ -395,24 +395,6 @@ static void stream_int_notify(struct stream_interface *si)
 		ic->flags &= ~CF_READ_DONTWAIT;
 }
 
-/* The stream interface is only responsible for the connection during the early
- * states, before plugging a mux. Thus it should only care about CO_FL_ERROR
- * before CS_ST_EST, and after that it must absolutely ignore it since the mux
- * may hold pending data. This function returns true if such an error was
- * reported. Both the CS and the CONN must be valid.
- */
-static inline int si_is_conn_error(const struct stream_interface *si)
-{
-	struct connection *conn;
-
-	if (si->cs->state >= CS_ST_EST)
-		return 0;
-
-	conn = __cs_conn(si->cs);
-	BUG_ON(!conn);
-	return !!(conn->flags & CO_FL_ERROR);
-}
-
 /* Called by I/O handlers after completion.. It propagates
  * connection flags to the stream interface, updates the stream (which may or
  * may not take this opportunity to try to forward data), then update the