diff --git a/Cartesian_kernel/include/CGAL/Cartesian/function_objects.h b/Cartesian_kernel/include/CGAL/Cartesian/function_objects.h
index 2508e6f8f81..75fbbc0389f 100644
--- a/Cartesian_kernel/include/CGAL/Cartesian/function_objects.h
+++ b/Cartesian_kernel/include/CGAL/Cartesian/function_objects.h
@@ -631,9 +631,9 @@ namespace CartesianKernelFunctors {
     operator()(const Point_2& s1s, const Point_2& s1t, const Point_2& s2s, const Point_2& s2t) const
     {
       return compare_slopesC2(s1s.x(), s1s.y(),
-			      s1t.x(), s1t.y(),
-			      s2s.x(), s2s.y(),
-			      s2t.x(), s2t.y());
+                              s1t.x(), s1t.y(),
+                              s2s.x(), s2s.y(),
+                              s2t.x(), s2t.y());
     }
   };
 
diff --git a/Homogeneous_kernel/include/CGAL/Homogeneous/function_objects.h b/Homogeneous_kernel/include/CGAL/Homogeneous/function_objects.h
index 7123511b4d5..a099ce851d0 100644
--- a/Homogeneous_kernel/include/CGAL/Homogeneous/function_objects.h
+++ b/Homogeneous_kernel/include/CGAL/Homogeneous/function_objects.h
@@ -845,7 +845,7 @@ namespace HomogeneousKernelFunctors {
     operator()(const Segment_2& s1, const Segment_2& s2) const
     {
       return (*this)(s1.source(), s1.target(),
-		     s2.source(), s2.target());
+                     s2.source(), s2.target());
     }
 
     result_type
diff --git a/Kernel_23/doc/Kernel_23/Concepts/FunctionObjectConcepts.h b/Kernel_23/doc/Kernel_23/Concepts/FunctionObjectConcepts.h
index 20ef94b7df1..d4e17a99bfb 100644
--- a/Kernel_23/doc/Kernel_23/Concepts/FunctionObjectConcepts.h
+++ b/Kernel_23/doc/Kernel_23/Concepts/FunctionObjectConcepts.h
@@ -1048,7 +1048,7 @@ public:
   */
   Comparison_result operator()(const Kernel::Point_2& s1s,
                                const Kernel::Point_2& s1t,
-			       const Kernel::Point_2& s2s,
+                               const Kernel::Point_2& s2s,
                                const Kernel::Point_2& s2t));
 
   /// @}
@@ -9713,7 +9713,6 @@ public:
                            const Kernel::Point_3&s,
                            const Kernel::Point_3&t);
 
-
   /// @}
 
 }; /* end Kernel::SideOfOrientedSphere_3 */
diff --git a/Kernel_23/include/CGAL/Kernel/global_functions_2.h b/Kernel_23/include/CGAL/Kernel/global_functions_2.h
index a3a173a4446..a9a02be637f 100644
--- a/Kernel_23/include/CGAL/Kernel/global_functions_2.h
+++ b/Kernel_23/include/CGAL/Kernel/global_functions_2.h
@@ -351,7 +351,7 @@ template < class K >
 inline
 typename K::Comparison_result
 compare_slope(const Point_2<K> &s1s, const Point_2<K> &s1t,
-	      const Point_2<K> &s2s, const Point_2<K> &s2t)
+              const Point_2<K> &s2s, const Point_2<K> &s2t)
 {
   return internal::compare_slope(s1s, s1t, s2s, s2t, K());
 }