diff --git a/gen/src/Gen/Text.hs b/gen/src/Gen/Text.hs
index e8061d22c71..20df0dbf52d 100644
--- a/gen/src/Gen/Text.hs
+++ b/gen/src/Gen/Text.hs
@@ -6,7 +6,7 @@ module Gen.Text
     renameOperation,
     renameServiceFunction,
     renameService,
-    renameBranch,
+    renameEnumValue,
     renameReserved,
     lowerHead,
     upperHead,
@@ -54,8 +54,8 @@ renameService =
     . stripPrefix "Service"
     . stripSuffix "SDK"
 
-renameBranch :: Text -> (Text, Text)
-renameBranch = first go . join (,)
+renameEnumValue :: Text -> (Text, Text)
+renameEnumValue v = (go v, v)
   where
     go = Text.map (\c -> if Char.isAlphaNum c then c else '_') . upperHead
 
@@ -129,16 +129,16 @@ toCamelCase = toCamelCase' . Text.split (not . Char.isAlphaNum) . Text.dropWhile
 lowerHead :: Text -> Text
 lowerHead text
   | Text.all (\c -> Char.isUpper c || Char.isDigit c) text =
-    Text.toLower text
+      Text.toLower text
   | otherwise =
-    fromMaybe (mapHead Char.toLower text)
-      . msum
-      $ map
-        (\acronym -> mappend (Text.toLower acronym) <$> Text.stripPrefix acronym text)
-        [ "KMS",
-          "DB",
-          "MFA"
-        ]
+      fromMaybe (mapHead Char.toLower text)
+        . msum
+        $ map
+          (\acronym -> mappend (Text.toLower acronym) <$> Text.stripPrefix acronym text)
+          [ "KMS",
+            "DB",
+            "MFA"
+          ]
 
 upperHead :: Text -> Text
 upperHead = mapHead Char.toUpper
diff --git a/gen/src/Gen/Types/Service.hs b/gen/src/Gen/Types/Service.hs
index e4ff4e3310e..206cb7d0f1b 100644
--- a/gen/src/Gen/Types/Service.hs
+++ b/gen/src/Gen/Types/Service.hs
@@ -322,7 +322,7 @@ instance FromJSON (ShapeF ()) where
   parseJSON = Aeson.withObject "shape" $ \o -> do
     i <- Aeson.parseJSON (Aeson.Object o)
     t <- o .: "type"
-    m <- o .:? "enum"
+    enum <- o .:? "enum"
     ts <- o .:? "timestampFormat"
 
     case t of
@@ -338,9 +338,10 @@ instance FromJSON (ShapeF ()) where
       "boolean" -> pure (Lit i Bool)
       "timestamp" -> pure (Lit i (Time ts))
       "json" -> pure (Lit i Json)
-      "string" -> pure (maybe (Lit i Text) f m)
-        where
-          f = Enum i . HashMap.fromList . map (first mkId . renameBranch)
+      "string" -> pure $ case enum of
+        Nothing -> Lit i Text
+        Just values ->
+          Enum i . HashMap.fromList $ map (first mkId . renameEnumValue) values
       _ -> fail $ "Unknown Shape type: " ++ Text.unpack t
 
 data Operation f a b = Operation