diff --git a/changelog.md b/changelog.md
--- a/changelog.md
+++ b/changelog.md
@@ -1,5 +1,8 @@
 # mixed-types-num change log
 
+* v 0.5.1 2021-05-12
+  * if-then-else for CN-wrapped (see collect-error) condition
+  * Documentation now in README
 * v 0.5.0 2021-04-13
   * use package collect-errors with a much simpler CN wrapper
   * replace Maybe Bool by Kleenean (a new type)
diff --git a/mixed-types-num.cabal b/mixed-types-num.cabal
--- a/mixed-types-num.cabal
+++ b/mixed-types-num.cabal
@@ -4,10 +4,10 @@
 --
 -- see: https://github.com/sol/hpack
 --
--- hash: 46e51b8b8646d27d08cfb89dbe49874f7b1f16bce6d62ac284c8d7b4a5b0d7f4
+-- hash: ebf35143ac4aa16c68d0c397d0889437a815ea20e6e3ae5c9e7cf62648b7ea30
 
 name:           mixed-types-num
-version:        0.5.0.4
+version:        0.5.1.0
 synopsis:       Alternative Prelude with numeric and logic expressions typed bottom-up
 description:    Please see the README on GitHub at <https://github.com/michalkonecny/mixed-types-num#readme>
 category:       Math
diff --git a/src/Numeric/MixedTypes/Literals.hs b/src/Numeric/MixedTypes/Literals.hs
--- a/src/Numeric/MixedTypes/Literals.hs
+++ b/src/Numeric/MixedTypes/Literals.hs
@@ -107,6 +107,17 @@
     | b = e1
     | otherwise = e2
 
+instance 
+  (HasIfThenElse b t, CanTakeErrors es (IfThenElseType b t), CanBeErrors es) 
+  =>
+  (HasIfThenElse (CollectErrors es b) t)
+  where
+  type IfThenElseType (CollectErrors es b) t = IfThenElseType b t
+  ifThenElse (CollectErrors (Just b) es) e1 e2 = 
+    takeErrors es $ ifThenElse b e1 e2
+  ifThenElse (CollectErrors _ es) _ _ = 
+    takeErrorsNoValue es
+
 _testIf1 :: String
 _testIf1 = if True then "yes" else "no"