diff --git a/explicit-exception.cabal b/explicit-exception.cabal
--- a/explicit-exception.cabal
+++ b/explicit-exception.cabal
@@ -1,6 +1,6 @@
 Cabal-Version:    2.2
 Name:             explicit-exception
-Version:          0.2
+Version:          0.2.0.1
 License:          BSD-3-Clause
 License-File:     LICENSE
 Author:           Henning Thielemann <haskell@henning-thielemann.de>
@@ -41,7 +41,7 @@
 Source-Repository this
   type:     darcs
   location: https://hub.darcs.net/thielema/explicit-exception/
-  tag:      0.2
+  tag:      0.2.0.1
 
 Flag buildTests
   description: Build executables that demonstrate some space leaks
@@ -51,8 +51,8 @@
 Library
   Build-Depends:
     transformers >=0.2 && <0.7,
-    semigroups >=0.1 && <1.0,
-    deepseq >=1.1 && <1.5
+    semigroups >=0.1 && <1,
+    deepseq >=1.1 && <1.6
   If impl(jhc)
     Build-Depends:
       applicative >=1.0 && <1.1,
@@ -84,9 +84,9 @@
   If flag(buildTests)
     Build-Depends:
       explicit-exception,
-      bytestring >=0.9.0.1 && <0.12,
+      bytestring >=0.9.0.1 && <0.13,
       tar >=0.4 && <0.6,
-      base
+      base >=2 && <5
   Else
     Buildable: False
   GHC-Options: -Wall
@@ -98,8 +98,8 @@
   If flag(buildTests)
     Build-Depends:
       explicit-exception,
-      bytestring >=0.9.0.1 && <0.12,
-      base
+      bytestring >=0.9.0.1 && <0.13,
+      base >=2 && <5
   Else
     Buildable: False
   GHC-Options: -Wall
@@ -110,7 +110,7 @@
 Executable ee-unzip
   If flag(buildTests)
     Build-Depends:
-      base
+      base >=2 && <5
   Else
     Buildable: False
   GHC-Options: -Wall
@@ -122,7 +122,7 @@
   If flag(buildTests)
     Build-Depends:
       transformers,
-      base
+      base >=2 && <5
   Else
     Buildable: False
   GHC-Options: -Wall
diff --git a/src/Control/Monad/Exception/Synchronous.hs b/src/Control/Monad/Exception/Synchronous.hs
--- a/src/Control/Monad/Exception/Synchronous.hs
+++ b/src/Control/Monad/Exception/Synchronous.hs
@@ -204,6 +204,10 @@
       Success a   -> a
       Exception e -> handler e
 
+{-
+Semigroup instance could replace (Math.Checksum.IBAN.+++).
+-}
+
 -- like Applicative.<|>
 infixl 3 `alternative`, `alternativeT`
 
@@ -281,7 +285,8 @@
        in  a
 
 {-
-A MonadPlus instance would require another class, say DefaultException,
+An Alternative/MonadPlus instance would require another class,
+say DefaultException,
 that provides a default exception used for @mzero@.
 In Control.Monad.Error this is handled by the Error class.
 Since String is a typical type used for exceptions -