diff --git a/lib/Patat/Eval.hs b/lib/Patat/Eval.hs
index 0a85915..945831b 100644
--- a/lib/Patat/Eval.hs
+++ b/lib/Patat/Eval.hs
@@ -4,10 +4,9 @@
 module Patat.Eval
     ( parseEvalBlocks
 
-    , updateVar
     , evalVar
-    , evalVars
-    , forceEval
+    , evalActiveVars
+    , evalAllVars
     ) where
 
 
@@ -15,7 +14,7 @@ module Patat.Eval
 import qualified Control.Concurrent.Async       as Async
 import           Control.Exception              (IOException, catch, finally)
 import           Control.Monad                  (foldM, forever)
-import           Control.Monad.State            (StateT, evalStateT, state)
+import           Control.Monad.State            (StateT, runStateT, state)
 import           Control.Monad.Writer           (Writer, runWriter, tell)
 import           Data.Foldable                  (for_)
 import qualified Data.HashMap.Strict            as HMS
@@ -36,8 +35,9 @@ import qualified Text.Pandoc.Definition         as Pandoc
 --------------------------------------------------------------------------------
 parseEvalBlocks :: Presentation -> Presentation
 parseEvalBlocks presentation =
-    let (pres, evalBlocks) = runWriter $ evalStateT work zeroVarGen in
-    pres {pEvalBlocks = evalBlocks}
+    let ((pres, varGen), evalBlocks) = runWriter $
+            runStateT work (pVarGen presentation) in
+    pres {pEvalBlocks = evalBlocks, pVarGen = varGen}
   where
     work = case psEval (pSettings presentation) of
         Nothing -> pure presentation
@@ -108,12 +108,6 @@ evalBlock _ block =
     pure [Append [block]]
 
 
-
---------------------------------------------------------------------------------
-updateVar :: Var -> [Pandoc.Block] -> Presentation -> Presentation
-updateVar var blocks pres = pres {pVars = HMS.insert var blocks $ pVars pres}
-
-
 --------------------------------------------------------------------------------
 evalVar :: Var -> ([Pandoc.Block] -> IO ()) -> Presentation -> IO Presentation
 evalVar var writeOutput presentation = case HMS.lookup var evalBlocks of
@@ -162,17 +156,17 @@ evalVar var writeOutput presentation = case HMS.lookup var evalBlocks of
 
 
 --------------------------------------------------------------------------------
-evalVars
-    :: Foldable f
-    => f Var -> (Var -> [Pandoc.Block] -> IO ()) -> Presentation
-    -> IO Presentation
-evalVars vars update presentation =
-    foldM (\p var -> evalVar var (update var) p) presentation vars
+evalActiveVars
+    :: (Var -> [Pandoc.Block] -> IO ()) -> Presentation -> IO Presentation
+evalActiveVars update presentation = foldM
+    (\p var -> evalVar var (update var) p)
+    presentation
+    (activeVars presentation)
 
 
 --------------------------------------------------------------------------------
-forceEval :: Presentation -> IO Presentation
-forceEval pres = do
+evalAllVars :: Presentation -> IO Presentation
+evalAllVars pres = do
     updates <- IORef.newIORef []
 
     let forceEvalVar pres0 var = do
diff --git a/lib/Patat/Main.hs b/lib/Patat/Main.hs
index 1b351c8..d858945 100644
--- a/lib/Patat/Main.hs
+++ b/lib/Patat/Main.hs
@@ -161,7 +161,7 @@ main = do
             OA.parserFailure parserPrefs parserInfo
             (OA.ShowHelpText Nothing) mempty
 
-    errOrPres <- readPresentation filePath
+    errOrPres <- readPresentation zeroVarGen filePath
     pres      <- either (errorAndExit . return) return errOrPres
     let settings = pSettings pres
 
@@ -169,7 +169,7 @@ main = do
 
     if oDump options then
         EncodingFallback.withHandle IO.stdout (pEncodingFallback pres) $ do
-        Eval.forceEval pres >>= dumpPresentation
+        Eval.evalAllVars pres >>= dumpPresentation
     else
         -- (Maybe) initialize images backend.
         withMaybeHandle Images.withHandle (psImages settings) $ \images ->
@@ -211,10 +211,8 @@ loop app@App {..} = do
         (activeSpeakerNotes aPresentation)
 
     -- Start necessary eval blocks
-    presentation <- Eval.evalVars
-        (activeVars aPresentation)
-        (\var blocks -> Chan.writeChan aCommandChan $ PresentationCommand $
-            UpdateVar (pVersion aPresentation) var blocks)
+    presentation <- Eval.evalActiveVars
+        (\v -> Chan.writeChan aCommandChan . PresentationCommand . UpdateVar v)
         aPresentation
 
     size <- getPresentationSize presentation
diff --git a/lib/Patat/Presentation.hs b/lib/Patat/Presentation.hs
index d9cfd5d..ae3a60f 100644
--- a/lib/Patat/Presentation.hs
+++ b/lib/Patat/Presentation.hs
@@ -2,6 +2,10 @@ module Patat.Presentation
     ( PresentationSettings (..)
     , defaultPresentationSettings
 
+    , VarGen
+    , Var
+    , zeroVarGen
+
     , Presentation (..)
     , readPresentation
 
@@ -23,6 +27,7 @@ module Patat.Presentation
     ) where
 
 import           Patat.Presentation.Display
+import           Patat.Presentation.Instruction
 import           Patat.Presentation.Interactive
 import           Patat.Presentation.Internal
 import           Patat.Presentation.Read
diff --git a/lib/Patat/Presentation/Display.hs b/lib/Patat/Presentation/Display.hs
index c36d9de..8847d0d 100644
--- a/lib/Patat/Presentation/Display.hs
+++ b/lib/Patat/Presentation/Display.hs
@@ -161,7 +161,6 @@ dumpPresentation pres@Presentation {..} =
     dumpFragment :: Index -> [PP.Doc]
     dumpFragment idx =
         case displayPresentation (getSize idx) pres {pActiveFragment = idx} of
-            -- TODO: wait until everything is evaluated before dumping.
             DisplayDoc   doc      -> [doc]
             DisplayImage filepath -> [PP.string $ "{image: " ++ filepath ++ "}"]
 
diff --git a/lib/Patat/Presentation/Interactive.hs b/lib/Patat/Presentation/Interactive.hs
index e796f82..2c95851 100644
--- a/lib/Patat/Presentation/Interactive.hs
+++ b/lib/Patat/Presentation/Interactive.hs
@@ -14,7 +14,6 @@ module Patat.Presentation.Interactive
 
 --------------------------------------------------------------------------------
 import           Data.Char                      (isDigit)
-import qualified Patat.Eval                     as Eval
 import           Patat.Presentation.Instruction (Var)
 import           Patat.Presentation.Internal
 import           Patat.Presentation.Read
@@ -34,7 +33,7 @@ data PresentationCommand
     | Last
     | Reload
     | Seek Int
-    | UpdateVar Version Var [Pandoc.Block]
+    | UpdateVar Var [Pandoc.Block]
     | UnknownCommand String
     deriving (Eq, Show)
 
@@ -110,14 +109,11 @@ updatePresentation cmd presentation = case cmd of
     Seek n           -> pure $ goToSlide $ \_ -> (n - 1, 0)
     Reload           -> reloadPresentation
     UnknownCommand _ -> pure $ UpdatedPresentation presentation
-    UpdateVar v x b  -> pure $ UpdatedPresentation $
-        if v /= version then presentation else Eval.updateVar x b presentation
+    UpdateVar v b    -> pure $ UpdatedPresentation $ updateVar v b presentation
   where
     numSlides :: Presentation -> Int
     numSlides pres = length (pSlides pres)
 
-    version = pVersion presentation
-
     clip :: Index -> Presentation -> Index
     clip (slide, fragment) pres
         | slide    >= numSlides pres = (numSlides pres - 1, lastFragments - 1)
@@ -141,10 +137,9 @@ updatePresentation cmd presentation = case cmd of
         }
 
     reloadPresentation = do
-        errOrPres <- readPresentation (pFilePath presentation)
+        errOrPres <- readPresentation (pVarGen presentation) (pFilePath presentation)
         return $ case errOrPres of
             Left  err  -> ErroredPresentation err
             Right pres -> UpdatedPresentation $ pres
-                { pVersion        = Version (unVersion version + 1)
-                , pActiveFragment = clip (pActiveFragment presentation) pres
+                { pActiveFragment = clip (pActiveFragment presentation) pres
                 }
diff --git a/lib/Patat/Presentation/Internal.hs b/lib/Patat/Presentation/Internal.hs
index a29d871..cf469f2 100644
--- a/lib/Patat/Presentation/Internal.hs
+++ b/lib/Patat/Presentation/Internal.hs
@@ -3,8 +3,7 @@
 {-# LANGUAGE OverloadedStrings          #-}
 {-# LANGUAGE TemplateHaskell            #-}
 module Patat.Presentation.Internal
-    ( Version (..)
-    , Breadcrumbs
+    ( Breadcrumbs
     , Presentation (..)
     , PresentationSettings (..)
     , defaultPresentationSettings
@@ -39,6 +38,8 @@ module Patat.Presentation.Internal
 
     , Size
     , getPresentationSize
+
+    , updateVar
     ) where
 
 
@@ -61,10 +62,6 @@ import qualified Skylighting                    as Skylighting
 import qualified Text.Pandoc                    as Pandoc
 
 
---------------------------------------------------------------------------------
-newtype Version = Version {unVersion :: Int} deriving (Eq, Show)
-
-
 --------------------------------------------------------------------------------
 type Breadcrumbs = [(Int, [Pandoc.Inline])]
 
@@ -72,7 +69,6 @@ type Breadcrumbs = [(Int, [Pandoc.Inline])]
 --------------------------------------------------------------------------------
 data Presentation = Presentation
     { pFilePath         :: !FilePath
-    , pVersion          :: !Version
     , pEncodingFallback :: !EncodingFallback
     , pTitle            :: ![Pandoc.Inline]
     , pAuthor           :: ![Pandoc.Inline]
@@ -84,6 +80,7 @@ data Presentation = Presentation
     , pActiveFragment   :: !Index
     , pSyntaxMap        :: !Skylighting.SyntaxMap
     , pEvalBlocks       :: !Eval.EvalBlocks
+    , pVarGen           :: !Instruction.VarGen
     , pVars             :: !(HMS.HashMap Instruction.Var [Pandoc.Block])
     }
 
@@ -203,3 +200,8 @@ getPresentationSize pres = do
     pure $ Size {sRows = rows, sCols = cols}
   where
     settings = activeSettings pres
+
+
+--------------------------------------------------------------------------------
+updateVar :: Instruction.Var -> [Pandoc.Block] -> Presentation -> Presentation
+updateVar var blocks pres = pres {pVars = HMS.insert var blocks $ pVars pres}
diff --git a/lib/Patat/Presentation/Read.hs b/lib/Patat/Presentation/Read.hs
index 3405b55..bd0af50 100644
--- a/lib/Patat/Presentation/Read.hs
+++ b/lib/Patat/Presentation/Read.hs
@@ -32,6 +32,7 @@ import qualified Patat.Eval                     as Eval
 import qualified Patat.Presentation.Comments    as Comments
 import           Patat.Presentation.Fragment
 import qualified Patat.Presentation.Instruction as Instruction
+import           Patat.Presentation.Instruction (VarGen)
 import           Patat.Presentation.Internal
 import           Patat.Transition               (parseTransitionSettings)
 import           Prelude
@@ -47,8 +48,8 @@ import qualified Text.Pandoc.Extended           as Pandoc
 
 
 --------------------------------------------------------------------------------
-readPresentation :: FilePath -> IO (Either String Presentation)
-readPresentation filePath = runExceptT $ do
+readPresentation :: VarGen -> FilePath -> IO (Either String Presentation)
+readPresentation varGen filePath = runExceptT $ do
     -- We need to read the settings first.
     (enc, src)   <- liftIO $ EncodingFallback.readFile filePath
     homeSettings <- ExceptT readHomeSettings
@@ -71,7 +72,7 @@ readPresentation filePath = runExceptT $ do
         Right x -> return x
 
     pres <- ExceptT $ pure $
-        pandocToPresentation filePath enc settings syntaxMap doc
+        pandocToPresentation varGen filePath enc settings syntaxMap doc
     pure $ Eval.parseEvalBlocks pres
   where
     ext = takeExtension filePath
@@ -122,12 +123,11 @@ readExtension (ExtensionList extensions) fileExt = case fileExt of
 
 --------------------------------------------------------------------------------
 pandocToPresentation
-    :: FilePath -> EncodingFallback -> PresentationSettings
+    :: VarGen -> FilePath -> EncodingFallback -> PresentationSettings
     -> Skylighting.SyntaxMap -> Pandoc.Pandoc -> Either String Presentation
-pandocToPresentation pFilePath pEncodingFallback pSettings pSyntaxMap
+pandocToPresentation pVarGen pFilePath pEncodingFallback pSettings pSyntaxMap
         pandoc@(Pandoc.Pandoc meta _) = do
-    let !pVersion        = Version 0
-        !pTitle          = case Pandoc.docTitle meta of
+    let !pTitle          = case Pandoc.docTitle meta of
             []    -> [Pandoc.Str . T.pack . snd $ splitFileName pFilePath]
             title -> title
         !pSlides         = pandocToSlides pSettings pandoc