diff --git a/Data/Tag.hs b/Data/Tag.hs
new file mode 100644
index 0000000..8b0862f
--- /dev/null
+++ b/Data/Tag.hs
@@ -0,0 +1,11 @@
+-- | A wrapper around the 'Slug' interface.
+
+module Data.Tag where
+
+import Control.Monad.Catch
+import Data.Slug
+import Data.Text
+
+-- | Make a tag.
+mkTag :: MonadThrow m => Text -> m Slug
+mkTag = mkSlugLen 1 20
diff --git a/Handler/BannedTags.hs b/Handler/BannedTags.hs
index fe39d83..3139e1d 100644
--- a/Handler/BannedTags.hs
+++ b/Handler/BannedTags.hs
@@ -1,11 +1,12 @@
 module Handler.BannedTags where
 
+import Data.Slug (unSlug, Slug)
+import Data.Tag
 import Import
-import Data.Slug (unSlug, mkSlug, Slug)
 
 checkSlugs :: Monad m => Textarea -> m (Either Text [Slug])
 checkSlugs (Textarea t) =
-    return $ first tshow $ (mapM mkSlug $ filter (not . null) $ lines $ filter (/= '\r') t)
+    return $ first tshow $ (mapM mkTag $ filter (not . null) $ lines $ filter (/= '\r') t)
 
 fromSlugs :: [Slug] -> Textarea
 fromSlugs = Textarea . unlines . map unSlug
diff --git a/Handler/Package.hs b/Handler/Package.hs
index 68c6f02..5ac73c6 100644
--- a/Handler/Package.hs
+++ b/Handler/Package.hs
@@ -5,7 +5,7 @@
 module Handler.Package where
 
 import           Data.Char
-import           Data.Slug
+import           Data.Tag
 import qualified Data.Text as T
 import qualified Data.Text.Encoding as T
 import           Data.Time (addUTCTime)
@@ -200,7 +200,7 @@ postPackageTagR packageName =
         do mtag <- lookupPostParam "slug"
            case mtag of
              Just tag ->
-               do slug <- mkSlugLen 1 20 tag
+               do slug <- mkTag tag
                   void (runDB (P.insert (Tag packageName slug uid)))
              Nothing -> error "Need a slug"
 
@@ -214,7 +214,7 @@ postPackageUntagR packageName =
         do mtag <- lookupPostParam "slug"
            case mtag of
              Just tag ->
-               do slug <- mkSlugLen 1 20 tag
+               do slug <- mkTag tag
                   void (runDB (P.deleteWhere
                                  [TagPackage ==. packageName
                                  ,TagTag ==. slug
diff --git a/stackage-server.cabal b/stackage-server.cabal
index 2d38994..e72bb9e 100644
--- a/stackage-server.cabal
+++ b/stackage-server.cabal
@@ -22,6 +22,7 @@ library
                      Settings.StaticFiles
                      Settings.Development
                      Data.Slug
+                     Data.Tag
                      Data.BlobStore
                      Data.Hackage
                      Data.Hackage.Views