diff -ura notmuch-0.27/notmuch-show.c notmuch-0.27-patched/notmuch-show.c
--- notmuch-0.27/notmuch-show.c	2018-06-13 03:42:34.000000000 +0200
+++ notmuch-0.27-patched/notmuch-show.c	2018-07-11 10:32:56.000456518 +0200
@@ -291,6 +291,8 @@
     charset = g_mime_object_get_content_type_parameter (part, "charset");
     if (charset) {
 	GMimeFilter *charset_filter;
+	if (!strcmp(charset, "iso-8859-1"))
+	    charset = "CP1252";
 	charset_filter = g_mime_filter_charset_new (charset, "UTF-8");
 	/* This result can be NULL for things like "unknown-8bit".
 	 * Don't set a NULL filter as that makes GMime print