diff --git a/devtools/create_ultima/archive.cpp b/devtools/create_ultima/archive.cpp
index e8e8728be59..3b23d904d83 100644
--- a/devtools/create_ultima/archive.cpp
+++ b/devtools/create_ultima/archive.cpp
@@ -54,6 +54,8 @@ void Archive::save() {
 		_file.writeString(ae._name.c_str());
 		_file.writeLong(ae._offset);
 		_file.writeWord(ae._size);
+
+		dataOffset += ae._size;
 	}
 	if (_file.pos() % 2)
 		_file.writeByte(0);