diff --git a/README.md b/README.md
index 466ccc4..a32256e 100644
--- a/README.md
+++ b/README.md
@@ -68,6 +68,7 @@ Each `*/ensure` utility, accepts following options (eventually passed with secon
   - `%v` - To be replaced with short string representation of invalid value
   - `%n` - To be replaced with meaninfgul name (to be passed with `name` option) of validated value. Not effective if `name` option is not present
 - `name` - Meaningful name for validated value, to be used in error message, assuming it contains `%n` placeholder
+- `Error` - Alternative error constructor to be used (defaults to `TypeError`)
 
 ### Index