diff --git a/src/viewport.cpp b/src/viewport.cpp
--- a/src/viewport.cpp
+++ b/src/viewport.cpp
@@ -3472,7 +3472,7 @@ void InitializeSpriteSorter()
  * @param text unused
  * @return the cost of this operation or an error
  */
-CommandCost CmdScrollViewport(TileIndex tile, DoCommandFlag flags, uint32 p1, uint32 p2, const char *text)
+CommandCost CmdScrollViewport(TileIndex tile, DoCommandFlag flags, uint32 p1, uint32 p2, const std::string &text)
 {
 	if (_current_company != OWNER_DEITY) return CMD_ERROR;
 	ViewportScrollTarget target = (ViewportScrollTarget)p1;