diff --git a/CHANGELOG b/CHANGELOG
index 0ffbd4579..de06bcefc 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,6 +1,9 @@
 ikiwiki (3.20180106) UNRELEASED; urgency=medium
 
   * core: Don't send relative redirect URLs when behind a reverse proxy
+  * mdwn: Enable fenced code blocks, PHP Markdown Extra-style definition
+    lists and GitHub-style extensions to HTML tag syntax when used with
+    Discount >= 2.2.0 (Closes: #888055)
 
  -- Simon McVittie <smcv@debian.org>  Mon, 08 Jan 2018 10:51:10 +0000
 
diff --git a/IkiWiki/Plugin/mdwn.pm b/IkiWiki/Plugin/mdwn.pm
index 9f06c03f2..66116ae01 100644
--- a/IkiWiki/Plugin/mdwn.pm
+++ b/IkiWiki/Plugin/mdwn.pm
@@ -125,6 +125,31 @@ sub htmlize (@) {
 						$flags |= 0x00400000;
 					}
 
+					# Enable fenced code blocks in libmarkdown >= 2.2.0
+					# https://bugs.debian.org/888055
+					if (Text::Markdown::Discount->can("MKD_FENCEDCODE")) {
+						$flags |= Text::Markdown::Discount::MKD_FENCEDCODE();
+					}
+					else {
+						$flags |= 0x02000000;
+					}
+
+					# PHP Markdown Extra-style term\n: definition -> <dl>
+					if (Text::Markdown::Discount->can("MKD_DLEXTRA")) {
+						$flags |= Text::Markdown::Discount::MKD_DLEXTRA();
+					}
+					else {
+						$flags |= 0x01000000;
+					}
+
+					# Allow dashes and underscores in tag names
+					if (Text::Markdown::Discount->can("MKD_GITHUBTAGS")) {
+						$flags |= Text::Markdown::Discount::MKD_GITHUBTAGS();
+					}
+					else {
+						$flags |= 0x08000000;
+					}
+
 					return Text::Markdown::Discount::markdown($t, $flags);
 				}
 			}