diff --git a/cabal-debian.cabal b/cabal-debian.cabal
--- a/cabal-debian.cabal
+++ b/cabal-debian.cabal
@@ -1,5 +1,5 @@
 Name:           cabal-debian
-Version:        5.0.1
+Version:        5.0.2
 Copyright:      Copyright (c) 2007-2014, David Fox, Jeremy Shaw; 2017-2020 Clint Adams
 License:        BSD3
 License-File:   LICENSE
diff --git a/src/Debian/Debianize/BuildDependencies.hs b/src/Debian/Debianize/BuildDependencies.hs
--- a/src/Debian/Debianize/BuildDependencies.hs
+++ b/src/Debian/Debianize/BuildDependencies.hs
@@ -78,7 +78,11 @@
 unboxDependency (BuildDepends d) = Just d
 unboxDependency (BuildTools d) = Just d
 unboxDependency (PkgConfigDepends d) = Just d
+#if MIN_VERSION_Cabal(3,0,0)
+unboxDependency (ExtraLibs _) = Nothing -- Dependency (PackageName d) anyVersion mempty
+#else
 unboxDependency (ExtraLibs _) = Nothing -- Dependency (PackageName d) anyVersion
+#endif
 
 -- |Debian packages don't have per binary package build dependencies,
 -- so we just gather them all up here.
@@ -113,9 +117,17 @@
 -- | Take the intersection of all the dependencies on a given package name
 mergeCabalDependencies :: [Dependency] -> [Dependency]
 mergeCabalDependencies =
+#if MIN_VERSION_Cabal(3,0,0)
+    List.map (foldl1 (\ (Dependency name range1 _) (Dependency _ range2 _) -> Dependency name (intersectVersionRanges range1 range2) mempty)) . groupBy ((==) `on` dependencyPackage) . sortBy (compare `on` dependencyPackage)
+#else
     List.map (foldl1 (\ (Dependency name range1) (Dependency _ range2) -> Dependency name (intersectVersionRanges range1 range2))) . groupBy ((==) `on` dependencyPackage) . sortBy (compare `on` dependencyPackage)
+#endif
     where
+#if MIN_VERSION_Cabal(3,0,0)
+      dependencyPackage (Dependency x _ _) = x
+#else
       dependencyPackage (Dependency x _) = x
+#endif
 
 -- The haskell-devscripts-minimal package contains the hlibrary.mk file with
 -- the rules for building haskell packages.
@@ -206,7 +218,11 @@
 -- documentation package for any libraries which are build
 -- dependencies, so we have use to all the cross references.
 docDependencies :: (MonadIO m) => Dependency_ -> CabalT m D.Relations
+#if MIN_VERSION_Cabal(3,0,0)
+docDependencies (BuildDepends (Dependency name ranges _)) =
+#else
 docDependencies (BuildDepends (Dependency name ranges)) =
+#endif
     do hc <- use (A.debInfo . D.flags . compilerFlavor)
        let hcs = singleton hc -- vestigial
        omitProfDeps <- use (A.debInfo . D.omitProfVersionDeps)
@@ -217,27 +233,46 @@
 -- libraries and the documentation packages, used for creating cross
 -- references.  Also the packages associated with extra libraries.
 buildDependencies :: (MonadIO m) => Set (CompilerFlavor, B.PackageType) -> Dependency_ -> CabalT m D.Relations
+#if MIN_VERSION_Cabal(3,0,0)
+buildDependencies hcTypePairs (BuildDepends (Dependency name ranges _)) =
+    use (A.debInfo . D.omitProfVersionDeps) >>= \ omitProfDeps ->
+    concat <$> mapM (\ (hc, typ) -> dependencies hc typ name ranges omitProfDeps) (toList hcTypePairs)
+#else
 buildDependencies hcTypePairs (BuildDepends (Dependency name ranges)) =
     use (A.debInfo . D.omitProfVersionDeps) >>= \ omitProfDeps ->
     concat <$> mapM (\ (hc, typ) -> dependencies hc typ name ranges omitProfDeps) (toList hcTypePairs)
+#endif
 buildDependencies _ dep@(ExtraLibs _) =
     do mp <- use (A.debInfo . D.execMap)
        return $ concat $ adapt mp dep
 buildDependencies _ dep =
     case unboxDependency dep of
+#if MIN_VERSION_Cabal(3,0,0)
+      Just (Dependency _name _ranges _) ->
+#else
       Just (Dependency _name _ranges) ->
+#endif
           do mp <- view (A.debInfo . D.execMap) <$> get
              return $ concat $ adapt mp dep
       Nothing ->
           return []
 
 adapt :: Map.Map String Relations -> Dependency_ -> [Relations]
+#if MIN_VERSION_Cabal(3,0,0)
+adapt mp (PkgConfigDepends (Dependency pkg _ _)) =
+    maybe (aptFile (unPackageName pkg)) (: []) (Map.lookup (unPackageName pkg) mp)
+adapt mp (BuildTools (Dependency pkg _ _)) =
+    maybe (aptFile (unPackageName pkg)) (: []) (Map.lookup (unPackageName pkg) mp)
+adapt _flags (ExtraLibs x) = [x]
+adapt _flags (BuildDepends (Dependency pkg _ _)) = [[[D.Rel (D.BinPkgName (unPackageName pkg)) Nothing Nothing]]]
+#else
 adapt mp (PkgConfigDepends (Dependency pkg _)) =
     maybe (aptFile (unPackageName pkg)) (: []) (Map.lookup (unPackageName pkg) mp)
 adapt mp (BuildTools (Dependency pkg _)) =
     maybe (aptFile (unPackageName pkg)) (: []) (Map.lookup (unPackageName pkg) mp)
 adapt _flags (ExtraLibs x) = [x]
 adapt _flags (BuildDepends (Dependency pkg _)) = [[[D.Rel (D.BinPkgName (unPackageName pkg)) Nothing Nothing]]]
+#endif
 
 -- There are three reasons this may not work, or may work
 -- incorrectly: (1) the build environment may be a different
diff --git a/src/Debian/Debianize/InputCabal.hs b/src/Debian/Debianize/InputCabal.hs
--- a/src/Debian/Debianize/InputCabal.hs
+++ b/src/Debian/Debianize/InputCabal.hs
@@ -39,7 +39,7 @@
 import Distribution.PackageDescription.Parse (readPackageDescription)
 #endif
 #endif
-import Distribution.Simple.Utils (defaultPackageDesc, die, setupMessage)
+import Distribution.Simple.Utils (defaultPackageDesc, die', setupMessage)
 import Distribution.System as Cabal (buildArch, Platform(..))
 import qualified Distribution.System as Cabal (buildOS)
 #if MIN_VERSION_Cabal(2,2,0)
@@ -109,4 +109,4 @@
             ret <- system "autoreconf"
             case ret of
               ExitSuccess -> return ()
-              ExitFailure n -> die ("autoreconf failed with status " ++ show n)
+              ExitFailure n -> die' verbose ("autoreconf failed with status " ++ show n)