diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,7 @@
+# 0.4.8.1
+
+* Added `HasCallStack` for some partial functions.
+
 # 0.4.8.0
 
 * Added `forOf_` and `forOf`.
diff --git a/microlens.cabal b/microlens.cabal
--- a/microlens.cabal
+++ b/microlens.cabal
@@ -1,5 +1,5 @@
 name:                microlens
-version:             0.4.8.0
+version:             0.4.8.1
 synopsis:            A tiny lens library with no dependencies. If you're writing an app, you probably want microlens-platform, not this.
 description:
   NOTE: If you're writing an app, you probably want <http://hackage.haskell.org/package/microlens-platform microlens-platform> – it has the most features. <http://hackage.haskell.org/package/microlens microlens> is intended more for library writers who want a tiny lens library (after all, lenses are pretty useful for everything, not just for updating records!).
diff --git a/src/Lens/Micro.hs b/src/Lens/Micro.hs
--- a/src/Lens/Micro.hs
+++ b/src/Lens/Micro.hs
@@ -1,13 +1,12 @@
-{-# LANGUAGE
-CPP,
-FlexibleInstances,
-FlexibleContexts,
-UndecidableInstances,
-RankNTypes,
-ScopedTypeVariables,
-MonoLocalBinds,
-Trustworthy
-  #-}
+{-# LANGUAGE CPP #-}
+{-# LANGUAGE FlexibleInstances #-}
+{-# LANGUAGE FlexibleContexts #-}
+{-# LANGUAGE UndecidableInstances #-}
+{-# LANGUAGE RankNTypes #-}
+{-# LANGUAGE ScopedTypeVariables #-}
+{-# LANGUAGE MonoLocalBinds #-}
+{-# LANGUAGE ConstraintKinds #-}
+{-# LANGUAGE Trustworthy #-}
 
 
 {- |
@@ -587,7 +586,7 @@
 {- |
 ('^?!') is an unsafe variant of ('^?') – instead of using 'Nothing' to indicate that there were no elements returned, it throws an exception.
 -}
-(^?!) :: s -> Getting (Endo a) s a -> a
+(^?!) :: HasCallStack => s -> Getting (Endo a) s a -> a
 s ^?! l = foldrOf l const (error "(^?!): empty Fold") s
 {-# INLINE (^?!) #-}
 
@@ -930,7 +929,7 @@
 
 >>> [] & singular each %~ negate
 -}
-singular :: Traversal s t a a -> Lens s t a a
+singular :: HasCallStack => Traversal s t a a -> Lens s t a a
 singular l afb s = case ins b of
   (w:ws) -> unsafeOuts b . (:ws) <$> afb w
   []     -> unsafeOuts b . return <$>
@@ -969,7 +968,7 @@
 infixl 5 `failing`
 
 {- |
-'filtered' is a traversal that filters elements “passing” thru it:
+'filtered' is a traversal that filters elements “passing” through it:
 
 >>> (1,2,3,4) ^.. each
 [1,2,3,4]
@@ -1032,7 +1031,7 @@
 pairedWithEvens = 'each' '.' 'filtered' ('even' '.' 'fst') '.' '_2'
 @
 
-Since you can't do anything with the 1st components thru this traversal, the following holds for any @f@ and @g@:
+Since you can't do anything with the 1st components through this traversal, the following holds for any @f@ and @g@:
 
 @
 'over' pairedWithEvens f '.' 'over' pairedWithEvens g = 'over' pairedWithEvens (f '.' g)
diff --git a/src/Lens/Micro/Extras.hs b/src/Lens/Micro/Extras.hs
--- a/src/Lens/Micro/Extras.hs
+++ b/src/Lens/Micro/Extras.hs
@@ -1,6 +1,4 @@
-{-# LANGUAGE
-Trustworthy
-  #-}
+{-# LANGUAGE Trustworthy #-}
 
 
 {- |
diff --git a/src/Lens/Micro/Internal.hs b/src/Lens/Micro/Internal.hs
--- a/src/Lens/Micro/Internal.hs
+++ b/src/Lens/Micro/Internal.hs
@@ -1,16 +1,16 @@
-{-# LANGUAGE
-CPP,
-FlexibleContexts,
-FlexibleInstances,
-UndecidableInstances,
-RankNTypes,
-ScopedTypeVariables,
-KindSignatures,
-TypeFamilies,
-MultiParamTypeClasses,
-FunctionalDependencies,
-Unsafe
-  #-}
+{-# LANGUAGE CPP #-}
+{-# LANGUAGE FlexibleContexts #-}
+{-# LANGUAGE FlexibleInstances #-}
+{-# LANGUAGE UndecidableInstances #-}
+{-# LANGUAGE RankNTypes #-}
+{-# LANGUAGE ScopedTypeVariables #-}
+{-# LANGUAGE KindSignatures #-}
+{-# LANGUAGE TypeFamilies #-}
+{-# LANGUAGE MultiParamTypeClasses #-}
+{-# LANGUAGE FunctionalDependencies #-}
+{-# LANGUAGE ConstraintKinds #-}
+{-# LANGUAGE ImplicitParams #-}
+{-# LANGUAGE Unsafe #-}
 
 
 {- |
@@ -52,6 +52,9 @@
   Cons(..),
   Snoc(..),
   Strict(..),
+
+  -- * CallStack
+  HasCallStack,
 )
 where
 
@@ -78,6 +81,17 @@
 import Unsafe.Coerce
 #endif
 
+-- We don't depend on the call-stack package because building an extra
+-- package is likely slower than adding several lines of code here.
+#if MIN_VERSION_base(4,9,0)
+import GHC.Stack (HasCallStack)
+#elif MIN_VERSION_base(4,8,1)
+import qualified GHC.Stack as GHC
+type HasCallStack = (?callStack :: GHC.CallStack)
+#else
+import GHC.Exts (Constraint)
+type HasCallStack = (() :: Constraint)
+#endif
 
 {- |
 'traversed' traverses any 'Traversable' container (list, vector, @Map@, 'Maybe', you name it):
diff --git a/src/Lens/Micro/Type.hs b/src/Lens/Micro/Type.hs
--- a/src/Lens/Micro/Type.hs
+++ b/src/Lens/Micro/Type.hs
@@ -1,8 +1,6 @@
-{-# LANGUAGE
-CPP,
-RankNTypes,
-Safe
-  #-}
+{-# LANGUAGE CPP #-}
+{-# LANGUAGE RankNTypes #-}
+{-# LANGUAGE Safe #-}
 
 
 {- |