diff --git a/Cabal/Distribution/Compat/NonEmptySet.hs b/Cabal/Distribution/Compat/NonEmptySet.hs
index be48f0c4397..09516d6256f 100644
--- a/Cabal/Distribution/Compat/NonEmptySet.hs
+++ b/Cabal/Distribution/Compat/NonEmptySet.hs
@@ -4,6 +4,10 @@ module Distribution.Compat.NonEmptySet (
     NonEmptySet,
     -- * Construction
     singleton,
+    -- * Insertion
+    insert,
+    -- * Deletion
+    delete,
     -- * Conversions
     toNonEmpty,
     fromNonEmpty,
@@ -15,7 +19,7 @@ module Distribution.Compat.NonEmptySet (
     map,
 ) where
 
-import Prelude (Bool (..), Eq, Ord (..), Read, Show (..), String, error, return, showParen, showString, ($), (++), (.))
+import Prelude (Bool (..), Eq, Maybe (..), Ord (..), Read, Show (..), String, error, otherwise, return, showParen, showString, ($), (++), (.))
 
 import Control.DeepSeq    (NFData (..))
 import Data.Data          (Data)
@@ -26,7 +30,7 @@ import Data.Typeable      (Typeable)
 import qualified Data.Foldable as F
 import qualified Data.Set      as Set
 
-import Distribution.Compat.Binary (Binary (..))
+import Distribution.Compat.Binary    (Binary (..))
 import Distribution.Utils.Structured
 
 #if MIN_VERSION_binary(0,6,0)
@@ -86,6 +90,24 @@ instance F.Foldable NonEmptySet where
 singleton :: a -> NonEmptySet a
 singleton = NES . Set.singleton
 
+-------------------------------------------------------------------------------
+-- Insertion
+-------------------------------------------------------------------------------
+
+insert :: Ord a => a -> NonEmptySet a -> NonEmptySet a
+insert x (NES xs) = NES (Set.insert x xs)
+
+-------------------------------------------------------------------------------
+-- Deletion
+-------------------------------------------------------------------------------
+
+delete :: Ord a => a -> NonEmptySet a -> Maybe (NonEmptySet a)
+delete x (NES xs)
+    | Set.null res = Nothing
+    | otherwise    = Just (NES xs)
+  where
+    res = Set.delete x xs
+
 -------------------------------------------------------------------------------
 -- Conversions
 -------------------------------------------------------------------------------
diff --git a/Cabal/Distribution/Types/Dependency.hs b/Cabal/Distribution/Types/Dependency.hs
index 8170f2b3db2..e8a3b53853a 100644
--- a/Cabal/Distribution/Types/Dependency.hs
+++ b/Cabal/Distribution/Types/Dependency.hs
@@ -25,7 +25,7 @@ import Distribution.Types.LibraryName
 import Distribution.Types.PackageName
 import Distribution.Types.UnqualComponentName
 
-import qualified Distribution.Compat.NonEmptySet as NonEmptySet
+import qualified Distribution.Compat.NonEmptySet as NES
 import qualified Text.PrettyPrint                as PP
 
 -- | Describes a dependency on a source package (API)
@@ -59,7 +59,7 @@ depLibraries (Dependency _ _ cs) = cs
 -- @since 3.4.0.0
 --
 mkDependency :: PackageName -> VersionRange -> NonEmptySet LibraryName -> Dependency
-mkDependency pn vr lb = Dependency pn vr (NonEmptySet.map conv lb)
+mkDependency pn vr lb = Dependency pn vr (NES.map conv lb)
   where
     pn' = packageNameToUnqualComponentName pn
 
@@ -71,6 +71,20 @@ instance Binary Dependency
 instance Structured Dependency
 instance NFData Dependency where rnf = genericRnf
 
+-- |
+--
+-- >>> prettyShow $ Dependency "pkg" anyVersion mainLibSet
+-- "pkg"
+--
+-- >>> prettyShow $ Dependency "pkg" anyVersion $ NES.insert (LSubLibName "sublib") mainLibSet
+-- "pkg:{pkg, sublib}"
+--
+-- >>> prettyShow $ Dependency "pkg" anyVersion $ NES.singleton (LSubLibName "sublib")
+-- "pkg:sublib"
+--
+-- >>> prettyShow $ Dependency "pkg" anyVersion $ NES.insert (LSubLibName "sublib-b") $ NES.singleton (LSubLibName "sublib-a")
+-- "pkg:{sublib-a, sublib-b}"
+--
 instance Pretty Dependency where
     pretty (Dependency name ver sublibs) = withSubLibs (pretty name) <+> pver
       where
@@ -78,11 +92,12 @@ instance Pretty Dependency where
         pver | isAnyVersionLight ver = PP.empty
              | otherwise             = pretty ver
 
-        withSubLibs doc
-            | sublibs == mainLibSet = doc
-            | otherwise          = doc <<>> PP.colon <<>> PP.braces prettySublibs
+        withSubLibs doc = case NES.toList sublibs of
+            [LMainLibName]   -> doc
+            [LSubLibName uq] -> doc <<>> PP.colon <<>> pretty uq
+            _                -> doc <<>> PP.colon <<>> PP.braces prettySublibs
 
-        prettySublibs = PP.hsep $ PP.punctuate PP.comma $ prettySublib <$> NonEmptySet.toList sublibs
+        prettySublibs = PP.hsep $ PP.punctuate PP.comma $ prettySublib <$> NES.toList sublibs
 
         prettySublib LMainLibName     = PP.text $ unPackageName name
         prettySublib (LSubLibName un) = PP.text $ unUnqualComponentName un
@@ -127,7 +142,7 @@ instance Parsec Dependency where
           _ <- char ':'
           versionGuardMultilibs
           parsecWarning PWTExperimental "colon specifier is experimental feature (issue #5660)"
-          NonEmptySet.singleton <$> parseLib <|> parseMultipleLibs
+          NES.singleton <$> parseLib <|> parseMultipleLibs
 
         spaces -- https://github.com/haskell/cabal/issues/5846
 
@@ -138,7 +153,7 @@ instance Parsec Dependency where
         parseMultipleLibs = between
             (char '{' *> spaces)
             (spaces *> char '}')
-            (NonEmptySet.fromNonEmpty <$> parsecCommaNonEmpty parseLib)
+            (NES.fromNonEmpty <$> parsecCommaNonEmpty parseLib)
 
 versionGuardMultilibs :: CabalParsing m => m ()
 versionGuardMultilibs = do
@@ -152,7 +167,7 @@ versionGuardMultilibs = do
 
 -- | Library set with main library.
 mainLibSet :: NonEmptySet LibraryName
-mainLibSet = NonEmptySet.singleton LMainLibName
+mainLibSet = NES.singleton LMainLibName
 
 -- | Simplify the 'VersionRange' expression in a 'Dependency'.
 -- See 'simplifyVersionRange'.
diff --git a/Cabal/tests/ParserTests/regressions/issue-5846.format b/Cabal/tests/ParserTests/regressions/issue-5846.format
index f0e119da0c0..42194892150 100644
--- a/Cabal/tests/ParserTests/regressions/issue-5846.format
+++ b/Cabal/tests/ParserTests/regressions/issue-5846.format
@@ -10,6 +10,6 @@ library
     default-language: Haskell2010
     build-depends:
         lib1:{a, b},
-        lib2:{c},
-        lib3:{d} >=1,
+        lib2:c,
+        lib3:d >=1,
         lib4:{a, b} >=1
diff --git a/cabal-testsuite/PackageTests/MultipleLibraries/T6894/cabal.out b/cabal-testsuite/PackageTests/MultipleLibraries/T6894/cabal.out
index b3e8aed99bd..f8a13f7425f 100644
--- a/cabal-testsuite/PackageTests/MultipleLibraries/T6894/cabal.out
+++ b/cabal-testsuite/PackageTests/MultipleLibraries/T6894/cabal.out
@@ -10,6 +10,6 @@ Preprocessing library 'sublib' for issue-6894..
 Building library 'sublib' for issue-6894..
 Warning: issue.cabal:7:30: colon specifier is experimental feature (issue #5660)
 Configuring library for issue-6894..
-Warning: The package has an extraneous version range for a dependency on an internal library: issue:{sublib} >=0 && ==6894. This version range includes the current package but isn't needed as the current package's library will always be used.
+Warning: The package has an extraneous version range for a dependency on an internal library: issue:sublib >=0 && ==6894. This version range includes the current package but isn't needed as the current package's library will always be used.
 Preprocessing library for issue-6894..
 Building library for issue-6894..