diff --git a/modules/Bio/EnsEMBL/DBSQL/AssemblyMapperAdaptor.pm b/modules/Bio/EnsEMBL/DBSQL/AssemblyMapperAdaptor.pm
index 79821811578ed27098fdac2dd7eebd32001a7af2..e3ff0bcc696a74358524c9b39ead00af2c93625f 100644
--- a/modules/Bio/EnsEMBL/DBSQL/AssemblyMapperAdaptor.pm
+++ b/modules/Bio/EnsEMBL/DBSQL/AssemblyMapperAdaptor.pm
@@ -184,10 +184,10 @@ sub fetch_by_CoordSystems {
     throw("cs2 argument must be a Bio::EnsEMBL::CoordSystem.");
   }
 
-  if($cs1->equals($cs2)) {
-    throw("Cannot create mapper between same coord systems: " .
-          $cs1->name . " " . $cs1->version);
-  }
+#  if($cs1->equals($cs2)) {
+#    throw("Cannot create mapper between same coord systems: " .
+#          $cs1->name . " " . $cs1->version);
+#  }
 
   if($cs1->is_top_level()) {
     return Bio::EnsEMBL::TopLevelAssemblyMapper->new($self, $cs1, $cs2);
diff --git a/modules/Bio/EnsEMBL/Slice.pm b/modules/Bio/EnsEMBL/Slice.pm
index 732396a4dd5934a2a678d2e4a3bc40ecd22ced61..301a2ade8d699909a220ed1e29856dbba4a5b150 100644
--- a/modules/Bio/EnsEMBL/Slice.pm
+++ b/modules/Bio/EnsEMBL/Slice.pm
@@ -2924,12 +2924,6 @@ sub project_to_slice {
   my $slice_cs = $self->coord_system();
 
 
-  # no mapping is needed if the requested coord system is the one we are in
-  # but we do need to check if some of the slice is outside of defined regions
-  if($slice_cs->equals($cs)) {
-    return $self->_constrain_to_region();
-  }
-
   my @projection;
   my $current_start = 1;