diff --git a/src/newgrf.cpp b/src/newgrf.cpp
--- a/src/newgrf.cpp
+++ b/src/newgrf.cpp
@@ -414,10 +414,10 @@ static GRFFile *GetFileByGRFID(uint32 gr
  * @param filename The filename to obtain the file for.
  * @return The file.
  */
-static GRFFile *GetFileByFilename(const char *filename)
+static GRFFile *GetFileByFilename(const std::string &filename)
 {
 	for (GRFFile * const file : _grf_files) {
-		if (strcmp(file->filename, filename) == 0) return file;
+		if (file->filename == filename) return file;
 	}
 	return nullptr;
 }
@@ -8882,7 +8882,7 @@ static void InitNewGRFFile(const GRFConf
  */
 GRFFile::GRFFile(const GRFConfig *config)
 {
-	this->filename = stredup(config->filename);
+	this->filename = config->filename;
 	this->grfid = config->ident.grfid;
 
 	/* Initialise local settings to defaults */
@@ -8922,7 +8922,6 @@ GRFFile::GRFFile(const GRFConfig *config
 
 GRFFile::~GRFFile()
 {
-	free(this->filename);
 	delete[] this->language_map;
 }
 
@@ -9186,7 +9185,7 @@ static void FinaliseCargoArray()
  * @param filename The filename of the newgrf this house was defined in.
  * @return Whether the given housespec is valid.
  */
-static bool IsHouseSpecValid(HouseSpec *hs, const HouseSpec *next1, const HouseSpec *next2, const HouseSpec *next3, const char *filename)
+static bool IsHouseSpecValid(HouseSpec *hs, const HouseSpec *next1, const HouseSpec *next2, const HouseSpec *next3, const std::string &filename)
 {
 	if (((hs->building_flags & BUILDING_HAS_2_TILES) != 0 &&
 				(next1 == nullptr || !next1->enabled || (next1->building_flags & BUILDING_HAS_1_TILE) != 0)) ||
@@ -9194,7 +9193,7 @@ static bool IsHouseSpecValid(HouseSpec *
 				(next2 == nullptr || !next2->enabled || (next2->building_flags & BUILDING_HAS_1_TILE) != 0 ||
 				next3 == nullptr || !next3->enabled || (next3->building_flags & BUILDING_HAS_1_TILE) != 0))) {
 		hs->enabled = false;
-		if (filename != nullptr) Debug(grf, 1, "FinaliseHouseArray: {} defines house {} as multitile, but no suitable tiles follow. Disabling house.", filename, hs->grf_prop.local_id);
+		if (!filename.empty()) Debug(grf, 1, "FinaliseHouseArray: {} defines house {} as multitile, but no suitable tiles follow. Disabling house.", filename, hs->grf_prop.local_id);
 		return false;
 	}
 
@@ -9204,13 +9203,13 @@ static bool IsHouseSpecValid(HouseSpec *
 	if (((hs->building_flags & BUILDING_HAS_2_TILES) != 0 && next1->population != 0) ||
 			((hs->building_flags & BUILDING_HAS_4_TILES) != 0 && (next2->population != 0 || next3->population != 0))) {
 		hs->enabled = false;
-		if (filename != nullptr) Debug(grf, 1, "FinaliseHouseArray: {} defines multitile house {} with non-zero population on additional tiles. Disabling house.", filename, hs->grf_prop.local_id);
+		if (!filename.empty()) Debug(grf, 1, "FinaliseHouseArray: {} defines multitile house {} with non-zero population on additional tiles. Disabling house.", filename, hs->grf_prop.local_id);
 		return false;
 	}
 
 	/* Substitute type is also used for override, and having an override with a different size causes crashes.
 	 * This check should only be done for NewGRF houses because grf_prop.subst_id is not set for original houses.*/
-	if (filename != nullptr && (hs->building_flags & BUILDING_HAS_1_TILE) != (HouseSpec::Get(hs->grf_prop.subst_id)->building_flags & BUILDING_HAS_1_TILE)) {
+	if (!filename.empty() && (hs->building_flags & BUILDING_HAS_1_TILE) != (HouseSpec::Get(hs->grf_prop.subst_id)->building_flags & BUILDING_HAS_1_TILE)) {
 		hs->enabled = false;
 		Debug(grf, 1, "FinaliseHouseArray: {} defines house {} with different house size then it's substitute type. Disabling house.", filename, hs->grf_prop.local_id);
 		return false;
@@ -9219,7 +9218,7 @@ static bool IsHouseSpecValid(HouseSpec *
 	/* Make sure that additional parts of multitile houses are not available. */
 	if ((hs->building_flags & BUILDING_HAS_1_TILE) == 0 && (hs->building_availability & HZ_ZONALL) != 0 && (hs->building_availability & HZ_CLIMALL) != 0) {
 		hs->enabled = false;
-		if (filename != nullptr) Debug(grf, 1, "FinaliseHouseArray: {} defines house {} without a size but marked it as available. Disabling house.", filename, hs->grf_prop.local_id);
+		if (!filename.empty()) Debug(grf, 1, "FinaliseHouseArray: {} defines house {} without a size but marked it as available. Disabling house.", filename, hs->grf_prop.local_id);
 		return false;
 	}
 
@@ -9297,7 +9296,7 @@ static void FinaliseHouseArray()
 
 		/* We need to check all houses again to we are sure that multitile houses
 		 * did get consecutive IDs and none of the parts are missing. */
-		if (!IsHouseSpecValid(hs, next1, next2, next3, nullptr)) {
+		if (!IsHouseSpecValid(hs, next1, next2, next3, std::string{})) {
 			/* GetHouseNorthPart checks 3 houses that are directly before
 			 * it in the house pool. If any of those houses have multi-tile
 			 * flags set it assumes it's part of a multitile house. Since
@@ -9606,7 +9605,7 @@ static void LoadNewGRFFileFromFile(GRFCo
  */
 void LoadNewGRFFile(GRFConfig *config, GrfLoadingStage stage, Subdirectory subdir, bool temporary)
 {
-	const char *filename = config->filename;
+	const std::string &filename = config->filename;
 
 	/* A .grf file is activated only if it was active when the game was
 	 * started.  If a game is loaded, only its active .grfs will be