diff --git a/src/autoreplace_func.h b/src/autoreplace_func.h
new file mode 100644
--- /dev/null
+++ b/src/autoreplace_func.h
@@ -0,0 +1,103 @@
+/* $Id$ */
+
+/** @file autoreplace_func.h Functions related to autoreplacing. */
+
+#ifndef AUTOREPLACE_FUNC_H
+#define AUTOREPLACE_FUNC_H
+
+#include "autoreplace_type.h"
+#include "player.h"
+
+/**
+ * Remove all engine replacement settings for the player.
+ * @param  erl The renewlist for a given player.
+ * @return The new renewlist for the player.
+ */
+void RemoveAllEngineReplacement(EngineRenewList *erl);
+
+/**
+ * Retrieve the engine replacement in a given renewlist for an original engine type.
+ * @param  erl The renewlist to search in.
+ * @param  engine Engine type to be replaced.
+ * @return The engine type to replace with, or INVALID_ENGINE if no
+ * replacement is in the list.
+ */
+EngineID EngineReplacement(EngineRenewList erl, EngineID engine, GroupID group);
+
+/**
+ * Add an engine replacement to the given renewlist.
+ * @param erl The renewlist to add to.
+ * @param old_engine The original engine type.
+ * @param new_engine The replacement engine type.
+ * @param flags The calling command flags.
+ * @return 0 on success, CMD_ERROR on failure.
+ */
+CommandCost AddEngineReplacement(EngineRenewList *erl, EngineID old_engine, EngineID new_engine, GroupID group, uint32 flags);
+
+/**
+ * Remove an engine replacement from a given renewlist.
+ * @param erl The renewlist from which to remove the replacement
+ * @param engine The original engine type.
+ * @param flags The calling command flags.
+ * @return 0 on success, CMD_ERROR on failure.
+ */
+CommandCost RemoveEngineReplacement(EngineRenewList *erl, EngineID engine, GroupID group, uint32 flags);
+
+/**
+ * Remove all engine replacement settings for the given player.
+ * @param p Player.
+ */
+static inline void RemoveAllEngineReplacementForPlayer(Player *p)
+{
+	RemoveAllEngineReplacement(&p->engine_renew_list);
+}
+
+/**
+ * Retrieve the engine replacement for the given player and original engine type.
+ * @param p Player.
+ * @param engine Engine type.
+ * @return The engine type to replace with, or INVALID_ENGINE if no
+ * replacement is in the list.
+ */
+static inline EngineID EngineReplacementForPlayer(const Player *p, EngineID engine, GroupID group)
+{
+	return EngineReplacement(p->engine_renew_list, engine, group);
+}
+
+/**
+ * Check if a player has a replacement set up for the given engine.
+ * @param p Player.
+ * @param  engine Engine type to be replaced.
+ * @return true if a replacement was set up, false otherwise.
+ */
+static inline bool EngineHasReplacementForPlayer(const Player *p, EngineID engine, GroupID group)
+{
+	return EngineReplacementForPlayer(p, engine, group) != INVALID_ENGINE;
+}
+
+/**
+ * Add an engine replacement for the player.
+ * @param p Player.
+ * @param old_engine The original engine type.
+ * @param new_engine The replacement engine type.
+ * @param flags The calling command flags.
+ * @return 0 on success, CMD_ERROR on failure.
+ */
+static inline CommandCost AddEngineReplacementForPlayer(Player *p, EngineID old_engine, EngineID new_engine, GroupID group, uint32 flags)
+{
+	return AddEngineReplacement(&p->engine_renew_list, old_engine, new_engine, group, flags);
+}
+
+/**
+ * Remove an engine replacement for the player.
+ * @param p Player.
+ * @param engine The original engine type.
+ * @param flags The calling command flags.
+ * @return 0 on success, CMD_ERROR on failure.
+ */
+static inline CommandCost RemoveEngineReplacementForPlayer(Player *p, EngineID engine, GroupID group, uint32 flags)
+{
+	return RemoveEngineReplacement(&p->engine_renew_list, engine, group, flags);
+}
+
+#endif /* AUTOREPLACE_FUNC_H */