-#define CAMEL_SEEKABLE_SUBSTREAM(obj) (GTK_CHECK_CAST((obj), CAMEL_SEEKABLE_SUBSTREAM_TYPE, CamelSeekableSubstream))
-#define CAMEL_SEEKABLE_SUBSTREAM_CLASS(k) (GTK_CHECK_CLASS_CAST ((k), CAMEL_SEEKABLE_SUBSTREAM_TYPE, CamelSeekableSubstreamClass))
-#define CAMEL_IS_SEEKABLE_SUBSTREAM(o) (GTK_CHECK_TYPE((o), CAMEL_SEEKABLE_SUBSTREAM_TYPE))
+#define CAMEL_SEEKABLE_SUBSTREAM(obj) (CAMEL_CHECK_CAST((obj), CAMEL_SEEKABLE_SUBSTREAM_TYPE, CamelSeekableSubstream))
+#define CAMEL_SEEKABLE_SUBSTREAM_CLASS(k) (CAMEL_CHECK_CLASS_CAST ((k), CAMEL_SEEKABLE_SUBSTREAM_TYPE, CamelSeekableSubstreamClass))
+#define CAMEL_IS_SEEKABLE_SUBSTREAM(o) (CAMEL_CHECK_TYPE((o), CAMEL_SEEKABLE_SUBSTREAM_TYPE))