diff --git a/ChangeLog.md b/ChangeLog.md
--- a/ChangeLog.md
+++ b/ChangeLog.md
@@ -1,5 +1,9 @@
 # Revision history for net-spider
 
+## 0.4.3.6  -- 2021-02-11
+
+* Confirm test with `doctest-0.18`.
+
 ## 0.4.3.5  -- 2020-12-30
 
 * Confirm test with `greskell-1.2.0.0`.
diff --git a/net-spider.cabal b/net-spider.cabal
--- a/net-spider.cabal
+++ b/net-spider.cabal
@@ -1,5 +1,5 @@
 name:                   net-spider
-version:                0.4.3.5
+version:                0.4.3.6
 author:                 Toshio Ito <debug.ito@gmail.com>
 maintainer:             Toshio Ito <debug.ito@gmail.com>
 license:                BSD3
@@ -136,7 +136,7 @@
   ghc-options:          -Wall -fno-warn-unused-imports "-with-rtsopts=-M512m"
   main-is:              DocTest.hs
   build-depends:        base,
-                        doctest >=0.13 && <0.18,
+                        doctest >=0.13 && <0.19,
                         doctest-discover >=0.1.0.7 && <0.3