diff --git a/src/strings_func.h b/src/strings_func.h
--- a/src/strings_func.h
+++ b/src/strings_func.h
@@ -205,6 +205,7 @@ void SetDParamMaxValue(uint n, uint64 ma
 void SetDParamMaxDigits(uint n, uint count, FontSize size = FS_NORMAL);
 
 void SetDParamStr(uint n, const char *str);
+void SetDParamStr(uint n, const std::string &str);
 
 void CopyInDParam(int offs, const uint64 *src, int num);
 void CopyOutDParam(uint64 *dst, int offs, int num);