diff --git a/src/command_type.h b/src/command_type.h
--- a/src/command_type.h
+++ b/src/command_type.h
@@ -443,7 +443,7 @@ enum CommandPauseLevel {
  * @param text Additional text
  * @return The CommandCost of the command, which can be succeeded or failed.
  */
-typedef CommandCost CommandProc(TileIndex tile, DoCommandFlag flags, uint32 p1, uint32 p2, const char *text);
+typedef CommandCost CommandProc(TileIndex tile, DoCommandFlag flags, uint32 p1, uint32 p2, const std::string &text);
 
 /**
  * Define a command with the flags which belongs to it.