diff --git a/documentation/17.05/eiffel/Tutorials/invitation-eiffel-i2e/i2e-design-contract-and-assertions.wiki b/documentation/17.05/eiffel/Tutorials/invitation-eiffel-i2e/i2e-design-contract-and-assertions.wiki
index 9a8e9208..53f3af4a 100644
--- a/documentation/17.05/eiffel/Tutorials/invitation-eiffel-i2e/i2e-design-contract-and-assertions.wiki
+++ b/documentation/17.05/eiffel/Tutorials/invitation-eiffel-i2e/i2e-design-contract-and-assertions.wiki
@@ -143,7 +143,7 @@ Under EiffelStudio you may also set up compilation options, for the whole system
 
 This ability to check assertions provides a powerful testing and debugging mechanism, in particular because the classes of the EiffelBase Libraries, widely used in Eiffel software development, are protected by carefully written assertions. 
 
-Run-time monitoring, however, is only one application of assertions, whose role as design and documentation aids, as part of theory of Design by Contract™, exerts a pervasive influence on the Eiffel style of software development. 
+Run-time monitoring, however, is only one application of assertions, whose role as design and documentation aids, as part of the theory of Design by Contract™, exerts a pervasive influence on the Eiffel style of software development.