diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,8 @@
+# optics-th-0.3.0.1 (2020-08-05)
+* Fix handling of nullary type families
+* Fix `declareFieldLabels` and `declareLenses` with DuplicateRecordFields
+* Improve documentation of `Optics.TH`
+
 # optics-th-0.3 (2020-04-15)
 * `optics-core-0.3` compatible release
 * GHC-8.10 support
diff --git a/optics-th.cabal b/optics-th.cabal
--- a/optics-th.cabal
+++ b/optics-th.cabal
@@ -1,5 +1,5 @@
 name:          optics-th
-version:       0.3
+version:       0.3.0.1
 license:       BSD3
 license-file:  LICENSE
 build-type:    Simple
@@ -59,4 +59,5 @@
   type:    exitcode-stdio-1.0
   main-is: Optics/TH/Tests.hs
 
-  other-modules: Optics.TH.Tests.T799
+  other-modules: Optics.TH.Tests.DuplicateRecordFields
+                 Optics.TH.Tests.T799
diff --git a/src/Optics/TH.hs b/src/Optics/TH.hs
--- a/src/Optics/TH.hs
+++ b/src/Optics/TH.hs
@@ -20,6 +20,7 @@
   , lensRules
   , lensRulesFor
   -- ** Single class per data type
+  -- $deprecatedClassy
   , makeClassy
   , makeClassy_
   , makeClassyFor
@@ -29,6 +30,7 @@
   , classyRules_
   , classyRulesFor
   -- ** Multiple classes per data type
+  -- $deprecatedFields
   , makeFields
   , makeFieldsNoPrefix
   , declareFields
@@ -90,8 +92,8 @@
 ----------------------------------------
 -- Labels
 
--- | Build field optics as instances of 'LabelOptic' class for use as overloaded
--- labels.
+-- | Build field optics as instances of the 'LabelOptic' class for use with
+-- overloaded labels.  See "Optics.Label" for how to use this pattern.
 --
 -- /e.g./
 --
@@ -124,11 +126,11 @@
 --     Dog x1 x2 -> point (Dog x1 x2)
 -- @
 --
--- which can be used as @#age@ and @#name@ with language extension
--- OverloadedLabels.
+-- which can be used as @#age@ and @#name@ with the @OverloadedLabels@ language
+-- extension.
 --
 -- /Note:/ if you wonder about the form of instances or why there is no label for
--- @animalAbsurd@, check documentation for 'LabelOptic'.
+-- @animalAbsurd@, see "Optics.Label#limitations".
 --
 -- @
 -- 'makeFieldOptics' = 'makeFieldLabelsWith' 'fieldLabelsRules'
@@ -340,6 +342,17 @@
 ----------------------------------------
 -- Classy
 
+-- $deprecatedClassy
+--
+-- This method of optics generation should only be used when migrating an
+-- existing codebase from the @lens@ library to @optics@ as it:
+--
+-- - Doesn't support prefixless fields.
+--
+-- - Doesn't support type changing updates.
+--
+-- See "Optics.Label" for our recommended pattern.
+
 -- | Make lenses and traversals for a type, and create a class when the type has
 -- no arguments.
 --
@@ -463,6 +476,27 @@
 
 ----------------------------------------
 -- Fields
+
+-- $deprecatedFields
+--
+-- This method of optics generation should only be used when migrating an
+-- existing codebase from the @lens@ library to @optics@ as it:
+--
+-- - Doesn't support type changing updates.
+--
+-- - Introduces tight coupling between types in your application as either all
+--   types need to be put in a single module (for @HasX@ class generation to
+--   work properly) or there needs to be a single, written by hand module with
+--   all the @HasX@ classes the application will use. Both approaches don't
+--   scale.
+--
+-- - Can't be leveraged by libraries because of the above problem lifted to the
+--   library level: there would have to exist a library with all possible @HasX@
+--   classes written by hand that is imported by all the other
+--   libraries. Otherwise for a given @field@ independent libraries would
+--   provide multiple @HasField@ classes incompatible with each other.
+--
+-- See "Optics.Label" for our recommended pattern.
 
 -- | Generate overloaded field accessors.
 --
diff --git a/src/Optics/TH/Internal/Product.hs b/src/Optics/TH/Internal/Product.hs
--- a/src/Optics/TH/Internal/Product.hs
+++ b/src/Optics/TH/Internal/Product.hs
@@ -28,6 +28,7 @@
 import qualified Data.Set as S
 import qualified Data.Traversable as T
 import qualified Language.Haskell.TH.Datatype as D
+import qualified Language.Haskell.TH.Syntax as TH
 
 import Data.Either.Optics
 import Data.Tuple.Optics
@@ -75,7 +76,7 @@
   do perDef <- lift $ do
        fieldCons <- traverse (normalizeConstructor info) cons
        let allFields  = toListOf (folded % _2 % folded % _1 % folded) fieldCons
-       let defCons    = over normFieldLabels (expandName allFields) fieldCons
+       let defCons    = over normFieldLabels (expandName rules tyName cons allFields) fieldCons
            allDefs    = setOf (normFieldLabels % folded) defCons
        T.sequenceA (M.fromSet (buildScaffold False rules s defCons) allDefs)
 
@@ -95,10 +96,35 @@
   normFieldLabels :: Traversal [(Name,[(a,Type)])] [(Name,[(b,Type)])] a b
   normFieldLabels = traversed % _2 % traversed % _1
 
-  -- Map a (possibly missing) field's name to zero-to-many optic definitions
-  expandName :: [Name] -> Maybe Name -> [DefName]
-  expandName allFields = concatMap (_fieldToDef rules tyName allFields) . maybeToList
+-- | Map a (possibly missing) field's name to zero-to-many optic definitions
+expandName :: LensRules -> Name -> [D.ConstructorInfo] -> [Name] -> Maybe Name -> [DefName]
+expandName rules tyName cons allFields =
+    concatMap (_fieldToDef rules tyName allFields . over nameString stripSel) . maybeToList
+  where
+    -- When DuplicateRecordFields is enabled, reified datatypes contain
+    -- "mangled" field names that look like $sel:foo:MkT where foo is the field
+    -- name and MkT is the first data constructor of the type (regardless of
+    -- whether that constructor contains the field or not).  If they are both
+    -- present, we strip off the prefix and suffix to get back to the underlying
+    -- field name.  See #323.
+    stripSel :: String -> String
+    stripSel n = fromMaybe n $ stripSuffix (':':first_con_name)
+                           =<< stripPrefix "$sel:" n
 
+    stripSuffix :: Eq a => [a] -> [a] -> Maybe [a]
+    stripSuffix suffix = fmap reverse . stripPrefix (reverse suffix) . reverse
+
+    -- We have to look up the actual name of the first constructor, rather than
+    -- trying to split the string on colons, because either the field name or
+    -- the constructor name might themselves contain colons.
+    first_con_name = case cons of
+      con:_ -> view nameString (D.constructorName con)
+      []    -> error "expandName: impossible for a record type with fields to have no constructors!"
+
+nameString :: Lens' Name String
+nameString = lens (\ (TH.Name (TH.OccName s) _) -> s)
+                  (\ (TH.Name _ f) s -> TH.Name (TH.OccName s) f)
+
 makeFieldLabelsForDec :: LensRules -> Dec -> DecsQ
 makeFieldLabelsForDec rules = makeFieldLabelsForDatatype rules <=< D.normalizeDec
 
@@ -113,7 +139,7 @@
   do perDef <- do
        fieldCons <- traverse (normalizeConstructor info) cons
        let allFields  = toListOf (folded % _2 % folded % _1 % folded) fieldCons
-       let defCons    = over normFieldLabels (expandName allFields) fieldCons
+       let defCons    = over normFieldLabels (expandName rules tyName cons allFields) fieldCons
            allDefs    = setOf (normFieldLabels % folded) defCons
        T.sequenceA (M.fromSet (buildScaffold True rules s defCons) allDefs)
 
@@ -135,10 +161,6 @@
     normFieldLabels :: Traversal [(Name,[(a,Type)])] [(Name,[(b,Type)])] a b
     normFieldLabels = traversed % _2 % traversed % _1
 
-    -- Map a (possibly missing) field's name to zero-to-many optic definitions
-    expandName :: [Name] -> Maybe Name -> [DefName]
-    expandName allFields = concatMap (_fieldToDef rules tyName allFields) . maybeToList
-
 makeFieldLabel
   :: LensRules
   -> (DefName, (OpticStab, [(Name, Int, [Int])]))
@@ -394,11 +416,12 @@
 
         go (VarT n) = modify' (S.delete n) *> pure Nothing
 
-        -- If type family is encountered, descend down and collect all of its
-        -- arguments for processing.
+        -- If a non-nullary type family is encountered, descend down and collect
+        -- all of its arguments for processing.
         go (ConT nm) = do
-          let getVarLen tf@(TypeFamilyHead _ varBndrs _ _) = (length varBndrs, tf, [])
-          preview (_FamilyI % _1 % typeFamilyHead % to getVarLen) <$> lift (reify nm)
+          let getVarLen = afolding $ \tf@(TypeFamilyHead _ varBndrs _ _) ->
+                if null varBndrs then Nothing else Just (length varBndrs, tf, [])
+          preview (_FamilyI % _1 % typeFamilyHead % getVarLen) <$> lift (reify nm)
 
         go (AppT ty1 ty2) = go ty1 >>= \case
           Just (n, tf, !args)
diff --git a/tests/Optics/TH/Tests.hs b/tests/Optics/TH/Tests.hs
--- a/tests/Optics/TH/Tests.hs
+++ b/tests/Optics/TH/Tests.hs
@@ -533,14 +533,19 @@
                          (Proxy (a' :: k'))
 checkKinded2Thing = #thing
 
+type family Fam0
+
 type family Fam (a :: k)
 type instance Fam Int = String
 
--- unambiguous type family application
-data FamRec1 a = FamRec1 { _famRec1Thing :: a -> Fam a }
+-- nullary type family + unambiguous type family application
+data FamRec1 a = FamRec1 { _famRec1Thing :: Fam0 -> a -> Fam a }
 makeFieldLabels ''FamRec1
 
-checkFamRec1Thing :: Iso (FamRec1 a) (FamRec1 b) (a -> Fam a) (b -> Fam b)
+checkFamRec1Thing :: Iso (FamRec1 a)
+                         (FamRec1 b)
+                         (Fam0 -> a -> Fam a)
+                         (Fam0 -> b -> Fam b)
 checkFamRec1Thing = #thing
 
 type family FamInj1 (a :: k) b = r | r -> a
diff --git a/tests/Optics/TH/Tests/DuplicateRecordFields.hs b/tests/Optics/TH/Tests/DuplicateRecordFields.hs
new file mode 100644
--- /dev/null
+++ b/tests/Optics/TH/Tests/DuplicateRecordFields.hs
@@ -0,0 +1,46 @@
+{-# LANGUAGE DataKinds #-}
+{-# LANGUAGE DuplicateRecordFields #-}
+{-# LANGUAGE FlexibleInstances #-}
+{-# LANGUAGE MultiParamTypeClasses #-}
+{-# LANGUAGE OverloadedLabels #-}
+{-# LANGUAGE TemplateHaskell #-}
+{-# LANGUAGE TypeFamilies #-}
+{-# LANGUAGE TypeOperators #-}
+{-# LANGUAGE UndecidableInstances #-}
+-- | Test that 'declareFieldLabels' and 'declareLenses' work in the presence of
+-- @DuplicateRecordFields@ (see issue #323), including when the data constructor
+-- or field name contain a colon, and with data families (because data families
+-- are weird).
+module Optics.TH.Tests.DuplicateRecordFields where
+
+import Optics.Core
+import Optics.TH
+
+$(declareFieldLabels [d|data T = Z | MkT { foo :: Int, (<:) :: Int -> Int }|])
+$(declareLenses [d|data U = MkU { foo :: Int, (<:) :: Int -> Int }|])
+$(declareLenses [d|data (:::) = (:::) { (>:) :: Int -> Int }|])
+
+foo' :: T -> [Int]
+foo' = toListOf #foo
+
+foo'' :: U -> Int
+foo'' = view foo
+
+(<::) :: U -> Int -> Int
+(<::) = view (<:)
+
+(>::) :: (:::) -> Int -> Int
+(>::) = view (>:)
+
+$(declareFieldLabels
+  [d|data family F x
+     data instance F Int = MkF { foo :: Int }|])
+$(declareLenses
+  [d|data family G x
+     data instance G Int = MkG { bar :: Int }|])
+
+foo''' :: F Int -> Int
+foo''' = view #foo
+
+bar' :: G Int -> Int
+bar' = view bar