diff --git a/README.md b/README.md
index 60c531c..f0030ed 100644
--- a/README.md
+++ b/README.md
@@ -117,7 +117,7 @@ The second of the '[SOLID](TODO)' principles. This principle states that entitie
 
 As a hypothetical example, imagine a module which is able to turn a Markdown document into HTML. If the module could be extended to handle a newly proposed markdown feature, without modifying the module internals, then it would be open for extension. If the module could _not_ be modified by a consumer so that how existing Markdown features are handled, then it would be _closed_ for modification.
 
-This principle has particular relevance for object-orientated programming, where we may design objects to be easily extended, but would avoid designing objects which can have their existing behaviour changed in unexpected ways.
+This principle has particular relevance for object-oriented programming, where we may design objects to be easily extended, but would avoid designing objects which can have their existing behaviour changed in unexpected ways.
 
 See also: