diff --git a/Circular_kernel_2/doc/Circular_kernel_2/Concepts/CircularKernel.h b/Circular_kernel_2/doc/Circular_kernel_2/Concepts/CircularKernel.h
index 40bb1ff2713..b7336312353 100644
--- a/Circular_kernel_2/doc/Circular_kernel_2/Concepts/CircularKernel.h
+++ b/Circular_kernel_2/doc/Circular_kernel_2/Concepts/CircularKernel.h
@@ -67,6 +67,11 @@ Model of `Kernel::Point_2`.
 */ 
 typedef Hidden_type Point_2; 
 
+/*! 
+Model of `Kernel::Line_2`. 
+*/ 
+typedef Hidden_type Line_2; 
+
 /*! 
 Model of `Kernel::Circle_2`. 
 */