diff --git a/Data/Ascii/Blaze.hs b/Data/Ascii/Blaze.hs
--- a/Data/Ascii/Blaze.hs
+++ b/Data/Ascii/Blaze.hs
@@ -5,6 +5,7 @@
 import Data.Ascii.ByteString
 
 -- base
+import Data.Monoid (Monoid)
 import Data.Semigroup (Semigroup)
 
 -- blaze-builder
diff --git a/Data/Ascii/ByteString.hs b/Data/Ascii/ByteString.hs
--- a/Data/Ascii/ByteString.hs
+++ b/Data/Ascii/ByteString.hs
@@ -7,6 +7,7 @@
 import Data.Typeable (Typeable)
 import Data.String (IsString (..))
 import qualified Data.Char as C
+import Data.Monoid (Monoid)
 import Data.Semigroup (Semigroup)
 
 -- bytestring
diff --git a/ascii.cabal b/ascii.cabal
--- a/ascii.cabal
+++ b/ascii.cabal
@@ -1,6 +1,6 @@
 Name:                ascii
-Version:             0.0.5.1
-Synopsis:            Type-safe, bytestring-based ASCII values.
+Version:             0.0.5.2
+Synopsis:            Type-safe, bytestring-based ASCII values
 Description:         Type-safe, bytestring-based ASCII values.
 License:             BSD3
 License-file:        LICENSE
@@ -12,6 +12,14 @@
 Bug-Reports:         https://github.com/typeclasses/ascii/issues
 Build-type:          Simple
 Cabal-version:       >= 1.6
+Tested-with:         GHC == 8.4.3
+                   , GHC == 8.2.2
+                   , GHC == 7.10.3
+                   , GHC == 7.8.4
+                   , GHC == 7.6.3
+                   , GHC == 7.4.2
+                   , GHC == 7.2.2
+                   , GHC == 7.0.4
 
 Source-Repository head
     Type:     git