diff --git a/src/newgrf.cpp b/src/newgrf.cpp
--- a/src/newgrf.cpp
+++ b/src/newgrf.cpp
@@ -2651,12 +2651,9 @@ static ChangeInfoResult LoadTranslationT
  */
 static std::string ReadDWordAsString(ByteReader *reader)
 {
-	char output[5];
-	for (int i = 0; i < 4; i++) output[i] = reader->ReadByte();
-	output[4] = '\0';
-	StrMakeValidInPlace(output, lastof(output));
-
-	return std::string(output);
+	std::string output;
+	for (int i = 0; i < 4; i++) output.push_back(reader->ReadByte());
+	return StrMakeValid(output);
 }
 
 /**