diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -56,3 +56,9 @@
 
 * Fifth version revised C. Improved the increasing and decreasing functions to reduce irregular and asymmetric
 behaviours for the polyrhythm module. Added the corresponding information to the README.md file.
+
+## 0.5.4.0 -- 2021-08-07
+
+* Fifth version revised D. Fixed issue with x == 0.0 for the long lines for the numeric increasing and decreasing
+functions for the polyrhythmicity.
+
diff --git a/Rhythmicity/PolyRhythm.hs b/Rhythmicity/PolyRhythm.hs
--- a/Rhythmicity/PolyRhythm.hs
+++ b/Rhythmicity/PolyRhythm.hs
@@ -216,7 +216,8 @@
  -> Double
  -> Double
 increasingF n x
- | n <= 0 || x <= 0 = error $ "Rhythmicity.PolyRhythm.increasingF: not defined for the arguments. " ++ show n ++ " " ++ show x
+ | n <= 0 || x < 0 = error $ "Rhythmicity.PolyRhythm.increasingF: not defined for the arguments. " ++ show n ++ " " ++ show x
+ | x == 0.0 = 0.001
  | n == 1 = x + min (x * 0.25) 0.125
  | x < 1 = x ** (1.0 / int2Double n)
  | x <= 1.1 = x + 1.0 / int2Double n
@@ -227,7 +228,8 @@
  -> Double
  -> Double
 decreasingF n x
- | n <= 0 || x <= 0 = error $ "Rhythmicity.PolyRhythm.decreasingF: not defined for the arguments. " ++ show n ++ " " ++ show x
+ | n <= 0 || x < 0 = error $ "Rhythmicity.PolyRhythm.decreasingF: not defined for the arguments. " ++ show n ++ " " ++ show x
+ | x == 0.0 = 0.000000000001
  | n == 1 = x - min (x * 0.25) 0.125
  | x < 1 = x ** int2Double n
  | x <= 1.1 = 1.0 / (x + 1.0 / int2Double n)
diff --git a/phonetic-languages-rhythmicity.cabal b/phonetic-languages-rhythmicity.cabal
--- a/phonetic-languages-rhythmicity.cabal
+++ b/phonetic-languages-rhythmicity.cabal
@@ -2,7 +2,7 @@
 -- For further documentation, see http://haskell.org/cabal/users-guide/
 
 name:                phonetic-languages-rhythmicity
-version:             0.5.3.0
+version:             0.5.4.0
 synopsis:            Allows to estimate the rhythmicity properties for the text
 description:         Allows to estimate (somewhat to say, evaluate) the rhythmicity properties for the text. Inspired by the ancient Greek and Latin poetry.