diff --git a/ChangeLog.md b/ChangeLog.md
--- a/ChangeLog.md
+++ b/ChangeLog.md
@@ -1,5 +1,9 @@
 # Revision history for greskell
 
+## 0.2.3.1  -- 2019-10-02
+
+* Confirm test with `semigroups-0.19.1`.
+
 ## 0.2.3.0  -- 2019-01-01
 
 * Add Extra module.
diff --git a/greskell.cabal b/greskell.cabal
--- a/greskell.cabal
+++ b/greskell.cabal
@@ -1,5 +1,5 @@
 name:                   greskell
-version:                0.2.3.0
+version:                0.2.3.1
 author:                 Toshio Ito <debug.ito@gmail.com>
 maintainer:             Toshio Ito <debug.ito@gmail.com>
 license:                BSD3
@@ -41,7 +41,7 @@
                         transformers >=0.5.2 && <0.6,
                         aeson >=0.11.2.1 && <1.5,
                         unordered-containers >=0.2.7.1 && <0.3,
-                        semigroups >=0.18.2 && <0.19,
+                        semigroups >=0.18.2 && <0.20,
                         vector >=0.12.0.1 && <0.13,
                         exceptions >=0.8.3 && <0.11
 
@@ -77,7 +77,7 @@
 flag hint-test
   description: Do tests that use Haskell interpreter (hint package).
                These tests depend on the behavior of the hint package, so it may be unstable.
-               Disable the flag to skip the tests.
+               Disable the flag to skip the tests. Or, maybe you should disable concurrent build.
   default: True
   manual: True
 
diff --git a/test/HintTest.hs b/test/HintTest.hs
--- a/test/HintTest.hs
+++ b/test/HintTest.hs
@@ -6,6 +6,7 @@
     setTopLevelModules, runInterpreter, InterpreterError,
     typeOf
   )
+import System.IO (hPutStrLn, stderr)
 import Test.Hspec
 
 main :: IO ()