diff --git a/ChangeLog.md b/ChangeLog.md
--- a/ChangeLog.md
+++ b/ChangeLog.md
@@ -1,5 +1,9 @@
 # Revision history for greskell-core
 
+## 0.1.3.6  -- 2021-02-11
+
+* Confirm test with `doctest-0.18`.
+
 ## 0.1.3.5  -- 2020-06-21
 
 * Confirm test with `base-4.14.0.0`
diff --git a/greskell-core.cabal b/greskell-core.cabal
--- a/greskell-core.cabal
+++ b/greskell-core.cabal
@@ -1,5 +1,5 @@
 name:                   greskell-core
-version:                0.1.3.5
+version:                0.1.3.6
 author:                 Toshio Ito <debug.ito@gmail.com>
 maintainer:             Toshio Ito <debug.ito@gmail.com>
 license:                BSD3
@@ -53,6 +53,7 @@
                         Data.Greskell.GraphSONSpec,
                         Data.Greskell.GMapSpec,
                         Data.Greskell.Test.QuickCheck
+  build-tool-depends:   hspec-discover:hspec-discover
   build-depends:        base, text, aeson, unordered-containers, vector,
                         greskell-core,
                         hspec >=2.2.3,
@@ -65,8 +66,9 @@
   hs-source-dirs:       test
   ghc-options:          -Wall -fno-warn-unused-imports "-with-rtsopts=-M512m"
   main-is:              DocTest.hs
+  build-tool-depends:   doctest-discover:doctest-discover, doctest:doctest
   build-depends:        base,
-                        doctest >=0.11 && <0.18,
+                        doctest >=0.11 && <0.19,
                         doctest-discover >=0.1.0.7 && <0.3