diff --git a/src/fios.h b/src/fios.h
index 0d9b170541..d5e0b9ff7a 100644
--- a/src/fios.h
+++ b/src/fios.h
@@ -32,7 +32,7 @@ typedef SmallMap<uint, CompanyProperties *> CompanyPropertiesMap;
 struct LoadCheckData {
 	bool checkable;     ///< True if the savegame could be checked by SL_LOAD_CHECK. (Old savegames are not checkable.)
 	StringID error;     ///< Error message from loading. INVALID_STRING_ID if no error.
-	char *error_data;   ///< Data to pass to SetDParamStr when displaying #error.
+	std::string error_msg; ///< Data to pass to SetDParamStr when displaying #error.
 
 	uint32 map_size_x, map_size_y;
 	TimerGameCalendar::Date current_date;
@@ -47,7 +47,7 @@ struct LoadCheckData {
 	struct LoggedAction *gamelog_action;          ///< Gamelog actions
 	uint gamelog_actions;                         ///< Number of gamelog actions
 
-	LoadCheckData() : error_data(nullptr), grfconfig(nullptr),
+	LoadCheckData() : grfconfig(nullptr),
 			grf_compatibility(GLC_NOT_FOUND), gamelog_action(nullptr), gamelog_actions(0)
 	{
 		this->Clear();
diff --git a/src/fios_gui.cpp b/src/fios_gui.cpp
index 11d74b5e4c..c358e4a597 100644
--- a/src/fios_gui.cpp
+++ b/src/fios_gui.cpp
@@ -49,8 +49,7 @@ void LoadCheckData::Clear()
 {
 	this->checkable = false;
 	this->error = INVALID_STRING_ID;
-	free(this->error_data);
-	this->error_data = nullptr;
+	this->error_msg.clear();
 
 	this->map_size_x = this->map_size_y = 256; // Default for old savegames which do not store mapsize.
 	this->current_date = 0;
@@ -500,7 +499,7 @@ public:
 			tr.top += FONT_HEIGHT_NORMAL;
 		} else if (_load_check_data.error != INVALID_STRING_ID) {
 			/* Incompatible / broken savegame */
-			SetDParamStr(0, _load_check_data.error_data);
+			SetDParamStr(0, _load_check_data.error_msg);
 			tr.top = DrawStringMultiLine(tr, _load_check_data.error, TC_RED);
 		} else {
 			/* Mapsize */
diff --git a/src/openttd.cpp b/src/openttd.cpp
index e919e80b66..380dcb3b4e 100644
--- a/src/openttd.cpp
+++ b/src/openttd.cpp
@@ -623,7 +623,7 @@ int openttd_main(int argc, char *argv[])
 				if (_load_check_data.HasErrors()) {
 					InitializeLanguagePacks(); // A language pack is needed for GetString()
 					char buf[256];
-					SetDParamStr(0, _load_check_data.error_data);
+					SetDParamStr(0, _load_check_data.error_msg);
 					GetString(buf, _load_check_data.error, lastof(buf));
 					fprintf(stderr, "%s\n", buf);
 				}
diff --git a/src/saveload/saveload.cpp b/src/saveload/saveload.cpp
index 0632451a71..0dc1baa10d 100644
--- a/src/saveload/saveload.cpp
+++ b/src/saveload/saveload.cpp
@@ -208,7 +208,7 @@ struct SaveLoadParams {
 	LoadFilter *lf;                      ///< Filter to read the savegame from.
 
 	StringID error_str;                  ///< the translatable error message to show
-	char *extra_msg;                     ///< the error message
+	std::string extra_msg;               ///< the error message
 
 	bool saveinprogress;                 ///< Whether there is currently a save in progress.
 };
@@ -330,17 +330,15 @@ static void SlNullPointers()
  * @note This function does never return as it throws an exception to
  *       break out of all the saveload code.
  */
-void NORETURN SlError(StringID string, const char *extra_msg)
+void NORETURN SlError(StringID string, const std::string &extra_msg)
 {
 	/* Distinguish between loading into _load_check_data vs. normal save/load. */
 	if (_sl.action == SLA_LOAD_CHECK) {
 		_load_check_data.error = string;
-		free(_load_check_data.error_data);
-		_load_check_data.error_data = (extra_msg == nullptr) ? nullptr : stredup(extra_msg);
+		_load_check_data.error_msg = extra_msg;
 	} else {
 		_sl.error_str = string;
-		free(_sl.extra_msg);
-		_sl.extra_msg = (extra_msg == nullptr) ? nullptr : stredup(extra_msg);
+		_sl.extra_msg = extra_msg;
 	}
 
 	/* We have to nullptr all pointers here; we might be in a state where
@@ -362,7 +360,7 @@ void NORETURN SlError(StringID string, const char *extra_msg)
  * @note This function does never return as it throws an exception to
  *       break out of all the saveload code.
  */
-void NORETURN SlErrorCorrupt(const char *msg)
+void NORETURN SlErrorCorrupt(const std::string &msg)
 {
 	SlError(STR_GAME_SAVELOAD_ERROR_BROKEN_SAVEGAME, msg);
 }
diff --git a/src/saveload/saveload_error.hpp b/src/saveload/saveload_error.hpp
index 77025f5a33..5a42257daa 100644
--- a/src/saveload/saveload_error.hpp
+++ b/src/saveload/saveload_error.hpp
@@ -13,8 +13,8 @@
 #include "../3rdparty/fmt/format.h"
 #include "../strings_type.h"
 
-void NORETURN SlError(StringID string, const char *extra_msg = nullptr);
-void NORETURN SlErrorCorrupt(const char *msg);
+void NORETURN SlError(StringID string, const std::string &extra_msg = {});
+void NORETURN SlErrorCorrupt(const std::string &msg);
 
 /**
  * Issue an SlErrorCorrupt with a format string.
@@ -28,7 +28,7 @@ void NORETURN SlErrorCorrupt(const char *msg);
 template <typename T, typename ... Args>
 static inline void NORETURN SlErrorCorruptFmt(const T &format, Args&&... fmt_args)
 {
-	SlErrorCorrupt(fmt::format(format, fmt_args...).c_str());
+	SlErrorCorrupt(fmt::format(format, fmt_args...));
 }
 
 #endif /* SAVELOAD_ERROR_HPP */