diff --git a/src/Monomer/Widgets/Composite.hs b/src/Monomer/Widgets/Composite.hs
index 6b1ed46e..77acff23 100644
--- a/src/Monomer/Widgets/Composite.hs
+++ b/src/Monomer/Widgets/Composite.hs
@@ -25,6 +25,7 @@ import Codec.CBOR.Decoding
 import Codec.CBOR.Encoding
 import Codec.Serialise
 import Control.Applicative ((<|>))
+import Control.Exception (AssertionFailed(..), throw)
 import Control.Lens (ALens', (&), (^.), (^?), (.~), (%~), (<>~), at, ix, non)
 import Data.Default
 import Data.List (foldl')
@@ -314,7 +315,7 @@ compositeMerge comp state wenv oldComp newComp = newResult where
   mergeRequired
     | isJust oldModel = modelChanged || (oldFlags /= newFlags)
     | otherwise = True
-  initRequired = not (instanceMatches tempRoot oldRoot)
+  initRequired = not (nodeMatches tempRoot oldRoot)
   tempResult
     | initRequired = widgetInit tempWidget cwenv tempRoot
     | otherwise = widgetMerge tempWidget cwenv oldRoot tempRoot
@@ -402,16 +403,18 @@ compositeRestore comp state wenv win newComp = result where
   }
   getBaseStyle wenv node = Nothing
   styledComp = initNodeStyle getBaseStyle wenv newComp
-  newResult = reduceResult comp newState wenv styledComp tempResult
+  reducedResult = reduceResult comp newState wenv styledComp tempResult
   widgetId = newComp ^. L.info . L.widgetId
-  path = newComp ^. L.info . L.path
-  result = newResult
-    & L.node . L.info . L.widgetId .~ oldInfo ^. L.widgetId
-    & L.node . L.info . L.viewport .~ oldInfo ^. L.viewport
-    & L.node . L.info . L.renderArea .~ oldInfo ^. L.renderArea
-    & L.node . L.info . L.sizeReqW .~ oldInfo ^. L.sizeReqW
-    & L.node . L.info . L.sizeReqH .~ oldInfo ^. L.sizeReqH
-    & L.requests %~ (UpdateWidgetPath widgetId path <|)
+  valid = infoMatches (win ^. L.info) (newComp ^. L.info)
+  message = matchFailedMsg (win ^. L.info) (newComp ^. L.info)
+  result
+    | valid = reducedResult
+        & L.node . L.info . L.widgetId .~ oldInfo ^. L.widgetId
+        & L.node . L.info . L.viewport .~ oldInfo ^. L.viewport
+        & L.node . L.info . L.renderArea .~ oldInfo ^. L.renderArea
+        & L.node . L.info . L.sizeReqW .~ oldInfo ^. L.sizeReqW
+        & L.node . L.info . L.sizeReqH .~ oldInfo ^. L.sizeReqH
+    | otherwise = throw (AssertionFailed $ "Restore failed. " ++ message)
 
 -- | Next focusable
 compositeFindNextFocus
diff --git a/src/Monomer/Widgets/Container.hs b/src/Monomer/Widgets/Container.hs
index 19ae033a..2479df9e 100644
--- a/src/Monomer/Widgets/Container.hs
+++ b/src/Monomer/Widgets/Container.hs
@@ -29,6 +29,7 @@ module Monomer.Widgets.Container (
 
 import Codec.Serialise
 import Control.Applicative ((<|>))
+import Control.Exception (AssertionFailed(..), throw)
 import Control.Lens ((&), (^.), (^?), (.~), (%~), _Just)
 import Control.Monad
 import Data.Default
@@ -388,9 +389,9 @@ mergeChildrenSeq wenv localKeys newNode oldItems newItems = res where
   mergedKey = widgetMerge newWidget wenv oldMatch newChild
   initNew = widgetInit newWidget wenv newChild
     & L.requests %~ (|> ResizeWidgets)
-  isMergeKey = isJust oldKeyMatch && instanceMatches newChild oldMatch
+  isMergeKey = isJust oldKeyMatch && nodeMatches newChild oldMatch
   (child, oldRest)
-    | instanceMatches newChild oldChild = (mergedOld, oldChildren)
+    | nodeMatches newChild oldChild = (mergedOld, oldChildren)
     | isMergeKey = (mergedKey, oldItems)
     | otherwise = (initNew, oldItems)
   (cmerged, cremoved)
@@ -477,7 +478,10 @@ restoreWrapper container wenv win newNode = newResult where
   postRes = case loadState (win ^. L.state) of
     Just state -> restorePostHandler wenv tmpRes state oldInfo newParent
     Nothing -> resultWidget newParent
+  valid = infoMatches (win ^. L.info) (newNode ^. L.info)
+  message = matchFailedMsg (win ^. L.info) (newNode ^. L.info)
   newResult
+    | not valid = throw (AssertionFailed $ "Restore failed. " ++ message)
     | isResizeResult (Just postRes) = postRes
         & L.node .~ updateSizeReq container wenv (postRes ^. L.node)
     | otherwise = postRes
diff --git a/src/Monomer/Widgets/Single.hs b/src/Monomer/Widgets/Single.hs
index 1769815a..7ad68c4c 100644
--- a/src/Monomer/Widgets/Single.hs
+++ b/src/Monomer/Widgets/Single.hs
@@ -13,6 +13,7 @@ module Monomer.Widgets.Single (
 ) where
 
 import Codec.Serialise
+import Control.Exception (AssertionFailed(..), throw)
 import Control.Lens ((&), (^.), (^?), (.~), _Just)
 import Data.Default
 import Data.Maybe
@@ -252,7 +253,11 @@ restoreWrapper single wenv win newNode = newResult where
   nodeHandler styledNode = case loadState (win ^. L.state) of
     Just state -> restoreHandler wenv state oldInfo styledNode
     _ -> resultWidget styledNode
-  newResult = loadStateHandler single wenv oldInfo newNode nodeHandler
+  valid = infoMatches (win ^. L.info) (newNode ^. L.info)
+  message = matchFailedMsg (win ^. L.info) (newNode ^. L.info)
+  newResult
+    | valid = loadStateHandler single wenv oldInfo newNode nodeHandler
+    | otherwise = throw (AssertionFailed $ "Restore failed. " ++ message)
 
 loadStateHandler
   :: (Typeable a, Serialise a)
diff --git a/src/Monomer/Widgets/Util/Widget.hs b/src/Monomer/Widgets/Util/Widget.hs
index c5faec07..219428c0 100644
--- a/src/Monomer/Widgets/Util/Widget.hs
+++ b/src/Monomer/Widgets/Util/Widget.hs
@@ -13,7 +13,9 @@ module Monomer.Widgets.Util.Widget (
   makeState,
   useState,
   loadState,
-  instanceMatches,
+  matchFailedMsg,
+  infoMatches,
+  nodeMatches,
   handleWidgetIdChange
 ) where
 
@@ -93,13 +95,22 @@ loadState state = state >>= wsVal >>= fromBS where
     Left _ -> Nothing
     Right val -> Just val
 
-instanceMatches :: WidgetNode s e -> WidgetNode s e -> Bool
-instanceMatches newNode oldNode = typeMatches && keyMatches where
-  oldInfo = oldNode ^. L.info
-  newInfo = newNode ^. L.info
+matchFailedMsg :: WidgetNodeInfo -> WidgetNodeInfo -> String
+matchFailedMsg oldInfo newInfo = message where
+  oldData = (oldInfo ^. L.widgetType, oldInfo ^. L.key)
+  newData = (newInfo ^. L.widgetType, newInfo ^. L.key)
+  message = "Nodes do not match: " ++ show oldData ++ " - " ++ show newData
+
+infoMatches :: WidgetNodeInfo -> WidgetNodeInfo -> Bool
+infoMatches oldInfo newInfo = typeMatches && keyMatches where
   typeMatches = oldInfo ^. L.widgetType == newInfo ^. L.widgetType
   keyMatches = oldInfo ^. L.key == newInfo ^. L.key
 
+nodeMatches :: WidgetNode s e -> WidgetNode s e -> Bool
+nodeMatches oldNode newNode = infoMatches oldInfo newInfo where
+  oldInfo = oldNode ^. L.info
+  newInfo = newNode ^. L.info
+
 handleWidgetIdChange :: WidgetNode s e -> WidgetResult s e -> WidgetResult s e
 handleWidgetIdChange oldNode result = newResult where
   oldPath = oldNode ^. L.info . L.path
diff --git a/tasks.md b/tasks.md
index 59e60f91..7a95b659 100644
--- a/tasks.md
+++ b/tasks.md
@@ -407,6 +407,7 @@
     - Make save/restore configurable (app)
     - Rebuild composite globalKeys
   - Automatically set new WidgetId/Path on Container
+  - Remove embedded fonts. Rely on loaded fonts, template will also include them
 
 - Pending
   - Add header in all files, indicating license and documenting what the module does
@@ -419,7 +420,7 @@
   - Add user documentation
 
 Maybe postponed after release?
-  - Remove embedded fonts. Rely on loaded fonts, template will also include them
+  - Restoring should fail if widget tree structure is different
   - Image
     - Fix crash when adding images
       - If called from render, immediate add seems to work.
@@ -444,7 +445,6 @@ Maybe postponed after release?
     - Test image updating WidgetId/Path
   - Create consistent, good looking, themes: dark, light, pastel
     - Import HTML color names: https://www.rapidtables.com/web/color/RGB_Color.html
-  - Restoring should fail if widget tree structure is different
   - Validate nested structures update correctly when disabling/enabling parent
   - Create DevelMain, take care of saving/loading state. Also provide a way of ignoring it.
   - Drag & drop for user (add attribute indicating if component supports being source/target)