diff --git a/Yst/Types.hs b/Yst/Types.hs
--- a/Yst/Types.hs
+++ b/Yst/Types.hs
@@ -21,18 +21,15 @@
 module Yst.Types
 where
 import Data.Char
-import qualified Data.HashMap.Strict as H
 import Data.Time
+import Data.String (fromString)
 import qualified Data.Text as T
 import Text.StringTemplate
 import Data.Aeson
+import Data.Aeson.KeyMap (KeyMap, foldrWithKey, insert)
 import qualified Data.Map as M
 import Data.Scientific (coefficient, base10Exponent)
 import Control.Monad
-#if MIN_VERSION_time(1,5,0)
-#else
-import System.Locale ( defaultTimeLocale )
-#endif
 
 data Site = Site {
     siteTitle     :: String
@@ -137,11 +134,11 @@
     | otherwise             = return $ NString $ show n
   parseJSON _ = return $ NNil
 
-handleMerges :: H.HashMap T.Text Value -> H.HashMap T.Text Value
-handleMerges = H.foldrWithKey go H.empty
-  where go k (Object h) m | isMerge k = H.foldrWithKey go m h
-        go k v m = H.insert k v m
-        isMerge k = k == T.pack "<<"
+handleMerges :: KeyMap Value -> KeyMap Value
+handleMerges = foldrWithKey go mempty
+  where go k (Object h) m | isMerge k = foldrWithKey go m h
+        go k v m = insert k v m
+        isMerge k = k == fromString "<<"
 
 instance ToJSON Node where
   toJSON (NDate s) = toJSON (NString $ formatTime defaultTimeLocale "%x" s)
diff --git a/changelog b/changelog
--- a/changelog
+++ b/changelog
@@ -1,3 +1,8 @@
+yst 0.7.1.3 (released 16 Jul 2022)
+
+  * Remove support for old versions of time (#54).
+  * Require aeson >= 2 and update code (#55).
+
 yst 0.7.1.2 (released 12 Aug 2021)
 
   * Use latest HStringTemplate so we can build with GHC 9.
diff --git a/yst.cabal b/yst.cabal
--- a/yst.cabal
+++ b/yst.cabal
@@ -1,6 +1,6 @@
 cabal-version:       2.2
 name:                yst
-version:             0.7.1.2
+version:             0.7.1.3
 build-type:          Simple
 synopsis:            Builds a static website from templates and data in YAML or
                      CSV files.
@@ -57,19 +57,16 @@
                      Paths_yst
   autogen-modules:   Paths_yst
   build-depends:     base >=3 && < 5,
-                     unordered-containers,
                      HStringTemplate >= 0.8.8,
                      csv,
-                     aeson >= 1.0,
+                     aeson >= 2.0,
                      yaml,
                      text,
                      scientific >= 0.2,
                      filepath,
                      containers,
                      directory,
-                     time,
-                     old-locale,
-                     old-time,
+                     time >= 1.5,
                      parsec,
                      lucid >= 2.9,
                      pandoc >= 2.14,