diff --git a/haskell-gi.cabal b/haskell-gi.cabal
--- a/haskell-gi.cabal
+++ b/haskell-gi.cabal
@@ -1,5 +1,5 @@
 name:                haskell-gi
-version:             0.21.0
+version:             0.21.1
 synopsis:            Generate Haskell bindings for GObject Introspection capable libraries
 description:         Generate Haskell bindings for GObject Introspection capable libraries. This includes most notably
                      Gtk+, but many other libraries in the GObject ecosystem provide introspection data too.
@@ -14,7 +14,7 @@
 stability:           Experimental
 category:            Development
 build-type:          Simple
-tested-with:         GHC == 7.8.4, GHC == 7.10.3, GHC == 8.0.1
+tested-with:         GHC == 7.8.4, GHC == 7.10.3, GHC == 8.0.1, GHC == 8.4.1
 cabal-version:       >=1.8
 
 extra-source-files: ChangeLog.md
@@ -27,7 +27,7 @@
   pkgconfig-depends:   gobject-introspection-1.0 >= 1.32, gobject-2.0 >= 2.32
   build-depends:       base >= 4.7 && < 5,
                        haskell-gi-base == 0.21.*,
-                       Cabal >= 1.20,
+                       Cabal >= 1.24,
                        attoparsec == 0.13.*,
                        containers,
                        directory,
diff --git a/lib/Data/GI/CodeGen/API.hs b/lib/Data/GI/CodeGen/API.hs
--- a/lib/Data/GI/CodeGen/API.hs
+++ b/lib/Data/GI/CodeGen/API.hs
@@ -58,7 +58,7 @@
 import Control.Applicative ((<$>))
 #endif
 
-import Control.Monad ((>=>), forM, forM_)
+import Control.Monad ((>=>), foldM, forM, forM_)
 import qualified Data.List as L
 import qualified Data.Map as M
 import Data.Maybe (mapMaybe, catMaybes)
@@ -149,7 +149,11 @@
 
 -- | A rule for modifying the GIR file.
 data GIRRule = GIRSetAttr (GIRPath, XML.Name) Text -- ^ (Path to element,
-                                                   -- attrName), newValue
+                                                   -- attrName), newValue.
+             | GIRAddNode GIRPath XML.Name -- ^ Add a child node at
+                                           -- the given selector.
+             | GIRDeleteNode GIRPath -- ^ Delete any nodes matching
+                                     -- the given selector.
              deriving (Show)
 
 data API
@@ -456,27 +460,65 @@
 -- otherwise return the element ummodified.
 fixupGIR :: [GIRRule] -> XML.Element -> XML.Element
 fixupGIR rules elem =
-    elem {XML.elementNodes = map (\e -> foldr applyGIRRule e rules)
-                             (XML.elementNodes elem)}
-    where applyGIRRule :: GIRRule -> XML.Node -> XML.Node
-          applyGIRRule (GIRSetAttr (path, attr) newVal) n =
-              girSetAttr (path, attr) newVal n
+    elem {XML.elementNodes =
+          mapMaybe (\e -> foldM applyGIRRule e rules) (XML.elementNodes elem)}
+    where applyGIRRule :: XML.Node -> GIRRule -> Maybe XML.Node
+          applyGIRRule n (GIRSetAttr (path, attr) newVal) =
+            Just $ girSetAttr (path, attr) newVal n
+          applyGIRRule n (GIRAddNode path new) =
+            Just $ girAddNode path new n
+          applyGIRRule n (GIRDeleteNode path) =
+            girDeleteNodes path n
 
 -- | Set an attribute for the child element specified by the given
 -- path.
 girSetAttr :: (GIRPath, XML.Name) -> Text -> XML.Node -> XML.Node
 girSetAttr (spec:rest, attr) newVal n@(XML.NodeElement elem) =
     if specMatch spec n
-    then if null rest -- Matched the full path, apply
-         then XML.NodeElement (elem {XML.elementAttributes =
-                                     M.insert attr newVal
-                                          (XML.elementAttributes elem)})
-         -- Still some selectors to apply
-         else XML.NodeElement (elem {XML.elementNodes =
-                                     map (girSetAttr (rest, attr) newVal)
-                                     (XML.elementNodes elem)})
+    then case rest of
+           -- Matched the full path, apply
+           [] -> XML.NodeElement (elem {XML.elementAttributes =
+                                        M.insert attr newVal
+                                        (XML.elementAttributes elem)})
+           -- Still some selectors to apply
+           _ -> XML.NodeElement (elem {XML.elementNodes =
+                                       map (girSetAttr (rest, attr) newVal)
+                                       (XML.elementNodes elem)})
     else n
 girSetAttr _ _ n = n
+
+-- | Add the given subnode to any nodes matching the given path
+girAddNode :: GIRPath -> XML.Name -> XML.Node -> XML.Node
+girAddNode (spec:rest) newNode n@(XML.NodeElement elem) =
+  if specMatch spec n
+  then case rest of
+    -- Matched the full path, add the new child node.
+    [] -> let newElement = XML.Element { elementName = newNode
+                                       , elementAttributes = M.empty
+                                       , elementNodes = [] }
+          in XML.NodeElement (elem {XML.elementNodes =
+                                    XML.elementNodes elem <>
+                                     [XML.NodeElement newElement]})
+    -- Still some selectors to apply.
+    _ -> XML.NodeElement (elem {XML.elementNodes =
+                                map (girAddNode rest newNode)
+                                 (XML.elementNodes elem)})
+  else n
+girAddNode _ _ n = n
+
+-- | Delete any nodes matching the given path.
+girDeleteNodes :: GIRPath -> XML.Node -> Maybe XML.Node
+girDeleteNodes (spec:rest) n@(XML.NodeElement elem) =
+  if specMatch spec n
+  then case rest of
+         -- Matched the full path, discard the node
+         [] -> Nothing
+         -- More selectors to apply
+         _ -> Just $ XML.NodeElement (elem {XML.elementNodes =
+                                            mapMaybe (girDeleteNodes rest)
+                                            (XML.elementNodes elem)})
+  else Just n
+girDeleteNodes _ n = Just n
 
 -- | Lookup the given attribute and if present see if it matches the
 -- given regex.
diff --git a/lib/Data/GI/CodeGen/Overrides.hs b/lib/Data/GI/CodeGen/Overrides.hs
--- a/lib/Data/GI/CodeGen/Overrides.hs
+++ b/lib/Data/GI/CodeGen/Overrides.hs
@@ -162,6 +162,10 @@
     withFlags $ parseNsVersion s
 parseOneLine (T.stripPrefix "set-attr " -> Just s) =
     withFlags $ parseSetAttr s
+parseOneLine (T.stripPrefix "add-node " -> Just s) =
+    withFlags $ parseAdd s
+parseOneLine (T.stripPrefix "delete-node " -> Just s) =
+    withFlags $ parseDelete s
 parseOneLine (T.stripPrefix "C-docs-url " -> Just u) =
     withFlags $ parseDocsUrl u
 parseOneLine (T.stripPrefix "if " -> Just s) = parseIf s
@@ -254,6 +258,27 @@
     throwError ("set-attr syntax is of the form\n" <>
                "\t\"set-attr nodePath attrName newValue\"\n" <>
                "Got \"set-attr " <> t <> "\" instead.")
+
+-- | Add the given child node to all nodes matching the path.
+parseAdd :: Text -> Parser ()
+parseAdd (T.words -> [path, name]) = do
+  pathSpec <- parsePathSpec path
+  parsedName <- parseXMLName name
+  tell $ defaultOverrides {girFixups = [GIRAddNode pathSpec parsedName]}
+parseAdd t =
+    throwError ("add-node syntax is of the form\n" <>
+               "\t\"add-node nodePath newName\"\n" <>
+               "Got \"add-node " <> t <> "\" instead.")
+
+-- | Delete all nodes matching the given path.
+parseDelete :: Text -> Parser ()
+parseDelete (T.words -> [path]) = do
+  pathSpec <- parsePathSpec path
+  tell $ defaultOverrides {girFixups = [GIRDeleteNode pathSpec]}
+parseDelete t =
+    throwError ("delete-node syntax is of the form\n" <>
+               "\t\"delete-node nodePath\"\n" <>
+               "Got \"delete-node " <> t <> "\" instead.")
 
 -- | Parse a documentation URL for the given module.
 parseDocsUrl :: Text -> Parser ()
diff --git a/lib/Data/GI/GIR/Allocation.hs b/lib/Data/GI/GIR/Allocation.hs
--- a/lib/Data/GI/GIR/Allocation.hs
+++ b/lib/Data/GI/GIR/Allocation.hs
@@ -27,5 +27,4 @@
                           allocCalloc = AllocationOpUnknown
                         , allocCopy = AllocationOpUnknown
                         , allocFree = AllocationOpUnknown
-
                         }