diff --git a/ChangeLog.md b/ChangeLog.md
--- a/ChangeLog.md
+++ b/ChangeLog.md
@@ -74,3 +74,7 @@
 ## 0.4.2.0 -- 2019-12-06
 
 * Fourth version revised H. The program if there is SoX installed in the system converts the .raw file to .wav file and deletes the first one to save space.
+
+## 0.4.2.1 -- 2019-12-06
+
+* Fourth version revised I. Minor improvements to documentation.
diff --git a/Main.hs b/Main.hs
--- a/Main.hs
+++ b/Main.hs
@@ -42,7 +42,7 @@
 -- header included). So, if you expect to create sounding for @n@ symbols of the Ukrainian text, provide at least @2 * (6792 - 44) * n + 44 = 13496 * n + 44@ (bytes) 
 -- of the additional space in the storage (in reality it can occupy much less because other data files are less in size). Afterwards, the program deletes 
 -- the .raw file (this will approximately halve the occupied space by the resulting file) and you can manually compress the .wav file 
--- (e. g. FLAC compression with the best ratio gives approxumately halving the size). Therefore, the resulting file 
+-- (e. g. FLAC compression with the best ratio gives approximately halving the size). Therefore, the resulting file 
 -- for the @mmsyn6ukr@ executable run prior to such operations without command line arguments is expected to be less than about @10^7@ bytes that is about 100 MB 
 -- (for 31416 symbols Ukrainian text).
 
diff --git a/mmsyn6ukr.cabal b/mmsyn6ukr.cabal
--- a/mmsyn6ukr.cabal
+++ b/mmsyn6ukr.cabal
@@ -2,7 +2,7 @@
 -- documentation, see http://haskell.org/cabal/users-guide/
 
 name:                mmsyn6ukr
-version:             0.4.2.0
+version:             0.4.2.1
 synopsis:            A musical instrument synthesizer or a tool for Ukrainian language listening
 description:         A program can be used as a musical instrument synthesizer or for Ukrainian speech synthesis especially for poets and writers
 homepage:            https://hackage.haskell.org/package/mmsyn6ukr