diff --git a/README.md b/README.md
index 0707bed..49cabca 100644
--- a/README.md
+++ b/README.md
@@ -12,12 +12,6 @@ gem 'parsec'
 
 * Use Ruby version 2.5.1
 
-#### Add to the top of your <filename> file
-
-```ruby
-require 'parsec'
-```
-
 #### You can then eval equations in your code
 
 ```ruby
@@ -26,18 +20,6 @@ parser.eval_equation('5 + 1')
 parser.eval_equation('(3 + 3) * (5 * 2)')
 ```
 
-#### You can also validate the formula syntax
-
-```ruby
-parser = Parsec::Parsec
-parser.validate_syntax('3>=2 ? 1 : 0') # correct syntax, returns true
-```
-
-```ruby
-parser = Parsec::Parsec
-parser.validate_syntax('3>=2 ? 1') # bad syntax, returns ArgumentError with appropriated message
-```
-
 #### Here are examples of equations which are accepted by the parser
 ```ruby
 parser = Parsec::Parsec
diff --git a/lib/string_to_boolean_refinements.rb b/lib/string_to_boolean_refinements.rb
index 152ccdf..1a1062e 100644
--- a/lib/string_to_boolean_refinements.rb
+++ b/lib/string_to_boolean_refinements.rb
@@ -3,7 +3,7 @@ module StringToBooleanRefinements
   refine String do
     def to_bool
       return true  if self == true  || self =~ /(true|t|yes|y|1|on)$/i
-      return false if self == false || blank? || self =~ /(false|f|no|n|0|off)$/i
+      return false if self == false || nil? || strip.empty? || self =~ /(false|f|no|n|0|off)$/i
       raise ArgumentError, "invalid value for Boolean: \"#{self}\""
     end
   end