diff --git a/Polygon/test/Polygon/SimplicityTest.cpp b/Polygon/test/Polygon/SimplicityTest.cpp
index eb3f32f26f0..f85e7fa3a5f 100644
--- a/Polygon/test/Polygon/SimplicityTest.cpp
+++ b/Polygon/test/Polygon/SimplicityTest.cpp
@@ -17,7 +17,7 @@ using std::endl;
 bool TestSimplicity(const char* FileName)
 // tests the simplicity of the polygon in the file FileName
 {
-  typedef Arithmetic_kernel::Rational NT;
+  typedef CGAL::Arithmetic_kernel::Rational NT;
   typedef CGAL::Cartesian<NT> K;
   typedef CGAL::Point_2<K> Point;