diff --git a/src/g_level.cpp b/src/g_level.cpp
index 43e2cdef1..a66ed99a9 100644
--- a/src/g_level.cpp
+++ b/src/g_level.cpp
@@ -1571,7 +1571,7 @@ void G_WriteSnapshots(TArray<FString> &filenames, TArray<FCompressedBuffer> &buf
 	{
 		if (wadlevelinfos[i].Snapshot.mCompressedSize > 0)
 		{
-			filename << wadlevelinfos[i].MapName << ".map.json";
+			filename.Format("%s.map.json", wadlevelinfos[i].MapName.GetChars());
 			filename.ToLower();
 			filenames.Push(filename);
 			buffers.Push(wadlevelinfos[i].Snapshot);
@@ -1579,7 +1579,7 @@ void G_WriteSnapshots(TArray<FString> &filenames, TArray<FCompressedBuffer> &buf
 	}
 	if (TheDefaultLevelInfo.Snapshot.mCompressedSize > 0)
 	{
-		filename << TheDefaultLevelInfo.MapName << ".mapd.json";
+		filename.Format("%s.mapd.json", TheDefaultLevelInfo.MapName.GetChars());
 		filename.ToLower();
 		filenames.Push(filename);
 		buffers.Push(TheDefaultLevelInfo.Snapshot);
diff --git a/src/serializer.h b/src/serializer.h
index 1592d41e0..17d8c970e 100644
--- a/src/serializer.h
+++ b/src/serializer.h
@@ -111,8 +111,11 @@ public:
 
 		if (BeginArray(key))
 		{
-			int max = ArraySize();
-			if (max < count) count = max;
+			if (isReading())
+			{
+				int max = ArraySize();
+				if (max < count) count = max;
+			}
 			for (int i = 0; i < count; i++)
 			{
 				Serialize(*this, nullptr, obj[i], (T*)nullptr);