diff --git a/notmuch-show.c b/notmuch-show.c
index 873a7c4c..8da3295e 100644
--- a/notmuch-show.c
+++ b/notmuch-show.c
@@ -471,9 +471,12 @@ show_text_part_content (GMimeObject *part, GMimeStream *stream_out)
 	/* This result can be NULL for things like "unknown-8bit".
 	 * Don't set a NULL filter as that makes GMime print
 	 * annoying assertion-failure messages on stderr. */
-	if (charset_filter)
+	if (charset_filter) {
 	    g_mime_stream_filter_add (GMIME_STREAM_FILTER (stream_filter),
 				      charset_filter);
+	    g_object_unref (charset_filter);
+	}
+
     }
 
     wrapper = g_mime_part_get_content_object (GMIME_PART (part));