diff --git a/changelog.md b/changelog.md
--- a/changelog.md
+++ b/changelog.md
@@ -1,5 +1,10 @@
 # Changelog for commonmark-extensions
 
+## 0.2.2
+
+  * Add footnote to gfmExtensions.  Note that this also requires
+    additional type constraints on gfmExtensions [API change].
+
 ## 0.2.1.2
 
 - Fix bug with absolute paths in rebase_relative_paths
diff --git a/commonmark-extensions.cabal b/commonmark-extensions.cabal
--- a/commonmark-extensions.cabal
+++ b/commonmark-extensions.cabal
@@ -1,5 +1,5 @@
 name:           commonmark-extensions
-version:        0.2.1.2
+version:        0.2.2
 synopsis:       Pure Haskell commonmark parser.
 description:
    This library provides some useful extensions to core commonmark
diff --git a/src/Commonmark/Extensions.hs b/src/Commonmark/Extensions.hs
--- a/src/Commonmark/Extensions.hs
+++ b/src/Commonmark/Extensions.hs
@@ -63,16 +63,18 @@
 import           Commonmark.Extensions.Wikilinks
 import           Commonmark.Extensions.RebaseRelativePaths
 import           Commonmark
+import           Data.Typeable
 #if !MIN_VERSION_base(4,11,0)
 import           Data.Monoid ((<>))
 #endif
 
 -- | Standard extensions for GitHub-flavored Markdown.
-gfmExtensions :: (Monad m, IsBlock il bl, IsInline il,
+gfmExtensions :: (Monad m, Typeable m, Typeable il, Typeable bl,
+                  IsBlock il bl, IsInline il, HasFootnote il bl,
                   HasEmoji il, HasStrikethrough il, HasPipeTable il bl,
                   HasTaskList il bl, ToPlainText il)
               => SyntaxSpec m il bl
 gfmExtensions =
   emojiSpec <> strikethroughSpec <> pipeTableSpec <> autolinkSpec <>
-    autoIdentifiersSpec <> taskListSpec
+    autoIdentifiersSpec <> taskListSpec <> footnoteSpec