diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,13 @@
 # Changelog
 
+## 4.0.1 (2020-10-22)
+
+#### Fixed
+
+- An infinite loop in `Version` comparison. [aura#652]
+
+[aura#652]: https://github.com/fosskers/aura/issues/652
+
 ## 4.0.0 (2020-10-20)
 
 #### Changed
diff --git a/Data/Versions.hs b/Data/Versions.hs
--- a/Data/Versions.hs
+++ b/Data/Versions.hs
@@ -80,6 +80,7 @@
 import           Data.List (intersperse)
 import           Data.List.NonEmpty (NonEmpty(..))
 import qualified Data.List.NonEmpty as NEL
+import           Data.Maybe (fromMaybe)
 import           Data.Text (Text)
 import qualified Data.Text as T
 import           Data.Void (Void)
@@ -521,36 +522,20 @@
 instance Semigroup Version where
   Version e c m r <> Version e' c' m' r' = Version ((+) <$> e <*> e') (c <> c') (m <> m') (r <> r')
 
--- | Set a `Version`'s epoch to `Nothing`.
-wipe :: Version -> Version
-wipe v = v { _vEpoch = Nothing }
-
 -- | Customized.
 instance Ord Version where
   -- | For the purposes of Versions with epochs, `Nothing` is the same as `Just 0`,
   -- so we need to compare their actual version numbers.
-  compare v0@(Version (Just 0) _ _ _) v1@(Version Nothing _ _ _) = compare (wipe v0) v1
-  compare v0@(Version Nothing _ _ _) v1@(Version (Just 0) _ _ _) = compare v0 (wipe v1)
-
-  -- | If a version has an epoch > 1 and the other has no epoch, the first will
-  -- be considered greater.
-  compare (Version (Just _) _ _ _) (Version Nothing _ _ _) = GT
-  compare (Version Nothing _ _ _) (Version (Just _) _ _ _) = LT
-
-  -- | If two epochs are equal, we need to compare their actual version numbers.
-  -- Otherwise, the comparison of the epochs is the only thing that matters.
-  compare v0@(Version (Just n) _ _ _) v1@(Version (Just m) _ _ _) | n == m = compare (wipe v0) (wipe v1)
-                                                                  | otherwise = compare n m
-
-  -- | The usual case. If first VChunks of each Version is equal, then we keep
-  -- recursing. Otherwise, we don't need to check further. Consider @1.2@
-  -- compared to @1.1.3.4.5.6@.
-  compare (Version _ as _ rs) (Version _ bs _ rs') = g (NEL.toList as) (NEL.toList bs)
+  compare (Version ae as _ rs) (Version be bs _ rs') = case compare (fromMaybe 0 ae) (fromMaybe 0 be) of
+    EQ  -> case g (NEL.toList as) (NEL.toList bs) of
+      -- If the two Versions were otherwise equal and recursed down this far,
+      -- we need to compare them by their "release" values.
+      EQ  -> g rs rs'
+      ord -> ord
+    ord -> ord
     where
       g :: [VChunk] -> [VChunk] -> Ordering
-      -- | If the two Versions were otherwise equal and recursed down this far,
-      -- we need to compare them by their "release" values.
-      g [] [] = g rs rs'
+      g [] [] = EQ
 
       -- | If all chunks up until this point were equal, but one side continues
       -- on with "lettered" sections, these are considered to be indicating a
diff --git a/test/Test.hs b/test/Test.hs
--- a/test/Test.hs
+++ b/test/Test.hs
@@ -20,6 +20,7 @@
 import           Test.Tasty.QuickCheck
 import           Text.Megaparsec
 import           Text.Megaparsec.Char
+import           Text.Printf (printf)
 
 ---
 
@@ -56,13 +57,14 @@
 goodVers :: [T.Text]
 goodVers = [ "1", "1.2", "1.0rc0", "1.0rc1", "1.1rc1", "1.58.0-3",  "44.0.2403.157-1"
            , "0.25-2",  "8.u51-1", "21-2", "7.1p1-1", "20150826-1", "1:0.10.16-3"
-           , "1.11.0.git.20200404-1", "1.11.0+20200830-1" ]
+           , "1.11.0.git.20200404-1", "1.11.0+20200830-1", "1:3.20" ]
 
 badVers :: [T.Text]
 badVers = ["", "1.2 "]
 
 messes :: [T.Text]
-messes = [ "10.2+0.93+1-1", "003.03-3", "002.000-7", "20.26.1_0-2", "1.6.0a+2014+m872b87e73dfb-1" ]
+messes = [ "10.2+0.93+1-1", "003.03-3", "002.000-7", "20.26.1_0-2", "1.6.0a+2014+m872b87e73dfb-1"
+         , "1.3.00.16851-1", "5.2.458699.0906-1" ]
 
 messComps :: [T.Text]
 messComps = [ "10.2+0.93+1-1", "10.2+0.93+1-2", "10.2+0.93+2-1"
@@ -172,26 +174,41 @@
         , testCase "0.25-2 is Version" $ check $ isVersion <$> versioning "0.25-2"
         , testCase "1:1.2.3-1 is Version" $ check $ isVersion <$> versioning "1:1.2.3-1"
         , testCase "1.2.3+1-1 is Version" $ check $ isVersion <$> versioning "1.2.3+1-1"
+        , testCase "1:3.20.1-1 is Version" $ check $ isVersion <$> versioning "1:3.20.1-1"
         , testCase "000.007-1 is Mess" $ check $ isMess <$> versioning "000.007-1"
         , testCase "20.26.1_0-2 is Mess" $ check $ isMess <$> versioning "20.26.1_0-2"
+        , testCase "1:3.20.1-1 is Version" $ check $ isVersion <$> versioning "1:3.20.1-1"
         ]
       , testGroup "Bad Versions" $
         map (\s -> testCase (T.unpack s) $ assertBool "A bad version parsed" $ isLeft $ versioning s) badVers
       , testGroup "Isomorphisms" $
         map (\s -> testCase (T.unpack s) $ isomorph s) $ goodSemVs ++ goodVers ++ messes
       , testGroup "Comparisons"
-        [ testCase "1.2.2r1-1 < 1.2.3-1"   $ comp versioning "1.2.2r1-1" "1.2.3-1"
-        , testCase "1.2.3-1   < 1.2.4r1-1" $ comp versioning "1.2.3-1" "1.2.4r1-1"
-        , testCase "1.2.3-1   < 2+0007-1"  $ comp versioning "1.2.3-1" "2+0007-1"
-        , testCase "1.2.3r1-1 < 2+0007-1"  $ comp versioning "1.2.3r1-1" "2+0007-1"
-        , testCase "1.2-5 < 1.2.3-1"       $ comp versioning "1.2-5" "1.2.3-1"
-        , testCase "1.6.0a+2014+m872b87e73dfb-1 < 1.6.0-1"
-          $ comp versioning "1.6.0a+2014+m872b87e73dfb-1" "1.6.0-1"
-        , testCase "1.11.0.git.20200404-1 < 1.11.0+20200830-1"
-          $ comp versioning "1.11.0.git.20200404-1" "1.11.0+20200830-1"
-        , testCase "0.17.0+r8+gc41db5f1-1 < 0.17.0+r157+g584760cf-1"
-          $ comp versioning "0.17.0+r8+gc41db5f1-1" "0.17.0+r157+g584760cf-1"
+        [ compVer "1.2.2r1-1" "1.2.3-1"
+        , compVer "1.2.3-1" "1.2.4r1-1"
+        , compVer "1.2.3-1" "2+0007-1"
+        , compVer "1.2.3r1-1" "2+0007-1"
+        , compVer "1.2-5" "1.2.3-1"
+        , compVer "1.6.0a+2014+m872b87e73dfb-1" "1.6.0-1"
+        , compVer "1.11.0.git.20200404-1" "1.11.0+20200830-1"
+        , compVer "0.17.0+r8+gc41db5f1-1" "0.17.0+r157+g584760cf-1"
+        , compVer "0.4.8-1" "0.4.9-1"
+        , compVer "7.42.13-4" "7.46.0-2"
+        , compVer "1.15.2-1" "1.15.3-1"
+        , compVer "2.1.16102-2" "2.1.17627-1"
+        , compVer "8.64.0.81-1" "8.65.0.78-1"
+        , compVer "1.3.00.16851-1" "1.3.00.25560-1"
+        , compVer "10.0.4-1" "10.1.0-1"
+        , compVer "1:3.20-1" "1:3.20.1-1"
+        , compVer "5.2.458699.0906-1" "5.3.472687.1012-1"
         ]
+      , testGroup "Equality"
+        [ eqVer "1:3.20.1-1"
+        , eqVer "1.3.00.25560-1"
+        , eqVer "150_28-3"
+        , eqVer "1.0.r15.g3fc772c-5"
+        , eqVer "0.88-2"
+        ]
       ]
     , testGroup "Lenses and Traversals"
       [ testCase "SemVer - Increment Patch" incPatch
@@ -205,6 +222,12 @@
     ]
   ]
 
+compVer :: T.Text -> T.Text -> TestTree
+compVer a b = testCase (printf "%s < %s" a b) $ comp versioning a b
+
+eqVer :: T.Text -> TestTree
+eqVer a = testCase (T.unpack a) $ equal versioning a
+
 -- | Does pretty-printing return a Versioning to its original form?
 isomorph :: T.Text -> Assertion
 isomorph t = case prettyV <$> versioning t of
@@ -235,6 +258,9 @@
 
 comp :: Ord b => (T.Text -> Either a b) -> T.Text -> T.Text -> Assertion
 comp f a b = check $ (<) <$> f a <*> f b
+
+equal :: Ord r => (T.Text -> Either l r) -> T.Text -> Assertion
+equal f a = check $ (\r -> compare r r == EQ) <$> f a
 
 check :: Either a Bool -> Assertion
 check = assertBool "Some Either-based assertion failed" . either (const False) id
diff --git a/versions.cabal b/versions.cabal
--- a/versions.cabal
+++ b/versions.cabal
@@ -1,6 +1,6 @@
 cabal-version:      2.2
 name:               versions
-version:            4.0.0
+version:            4.0.1
 synopsis:           Types and parsers for software version numbers.
 description:
   A library for parsing and comparing software version numbers. We like to give