diff --git a/src/Unused/Cache/DirectoryFingerprint.hs b/src/Unused/Cache/DirectoryFingerprint.hs
index d0b61a8..4c8799f 100644
--- a/src/Unused/Cache/DirectoryFingerprint.hs
+++ b/src/Unused/Cache/DirectoryFingerprint.hs
@@ -17,7 +17,7 @@ newtype MD5ExecutablePath = MD5ExecutablePath
 
 type MD5Config = ReaderT MD5ExecutablePath IO
 
-data FingerprintOutcome =
+newtype FingerprintOutcome =
     MD5ExecutableNotFound [String]
 
 sha :: IO (Either FingerprintOutcome String)
diff --git a/src/Unused/Types.hs b/src/Unused/Types.hs
index 6985d39..9b93916 100644
--- a/src/Unused/Types.hs
+++ b/src/Unused/Types.hs
@@ -70,11 +70,11 @@ data Removal = Removal
     , rReason :: String
     } deriving (Eq, Show)
 
-data GitContext = GitContext
+newtype GitContext = GitContext
     { gcCommits :: [GitCommit]
     } deriving (Eq, Show)
 
-data GitCommit = GitCommit
+newtype GitCommit = GitCommit
     { gcSha :: String
     } deriving (Eq, Show)