diff --git a/lib/Biodiverse/GUI/CellPopup.pm b/lib/Biodiverse/GUI/CellPopup.pm
index 4a113348d..15b1c4ce0 100644
--- a/lib/Biodiverse/GUI/CellPopup.pm
+++ b/lib/Biodiverse/GUI/CellPopup.pm
@@ -378,7 +378,7 @@ sub show_output_list {
             $model->set($iter,    0, $key ,  1, $val);
         }
     }
-    elsif (is_listref($list_ref)) {
+    elsif (is_arrayref($list_ref)) {
         my $numeric = 1;
         foreach my $key (@$list_ref) {
             if (! looks_like_number ($key)) {
@@ -394,7 +394,7 @@ sub show_output_list {
         
         my @keys = $numeric
             ? sort {$a <=> $b} @$list_ref
-            : natsort keys @$list_ref;
+            : natsort @$list_ref;
 
         foreach my $elt (@keys) {
             #print "[Cell popup] Adding output array entry $elt\n";
diff --git a/lib/Biodiverse/Indices/Indices.pm b/lib/Biodiverse/Indices/Indices.pm
index 308be12a1..ec0913e75 100644
--- a/lib/Biodiverse/Indices/Indices.pm
+++ b/lib/Biodiverse/Indices/Indices.pm
@@ -1567,8 +1567,11 @@ sub get_metadata_calc_element_lists_used {
 
     my %metadata = (
         name            => "Element lists",
-        description     => "Lists of elements used in neighbour sets 1 and 2.\n"
-                           . 'These form the basis for all the spatial calculations.',
+        description     =>
+            "[DEPRECATED] Lists of elements used in neighbour sets 1 and 2.\n"
+            . 'These form the basis for all the spatial calculations. '
+            . 'The return types are inconsistent. New code should use '
+            . 'calc_element_lists_used_as_arrays',
         type            => 'Lists and Counts',
         pre_calc        => 'calc_abc',
         uses_nbr_lists  => 1,  #  how many sets of lists it must have
@@ -1595,13 +1598,90 @@ sub get_metadata_calc_element_lists_used {
 
 sub calc_element_lists_used {
     my $self = shift;
+    my %args = @_;  #  rest of args into a hash
+
+    my $set1 = $args{element_list1};
+    my $set2 = $args{element_list2};
+    my $set3 = $args{element_list_all};
+
+    #  these two are hashes
+    if ($set1 && !is_hashref $set1) {
+        my $href = {};
+        @$href{@$set1} = (1) x @$set1;
+        $set1 = $href;
+    }
+    if ($set2 && !is_hashref $set2) {
+        my $href = {};
+        @$href{@$set2} = (1) x @$set2;
+        $set2 = $href;
+    }
+    #  this is an array
+    if ($set3 && is_hashref $set3) {
+        $set2 = [keys %$set3];
+    }
+
+    my %results = (
+        EL_LIST_SET1 => $set1,
+        EL_LIST_SET2 => $set2,
+        EL_LIST_ALL  => $set3,
+    );
+
+    return wantarray ? %results : \%results;
+}
 
+sub get_metadata_calc_element_lists_used_as_arrays {
+    my $self = shift;
+
+    my %metadata = (
+        name            => "Element arrays",
+        description     => "Arrays of elements used in neighbour sets 1 and 2.\n"
+            . 'These form the basis for all the spatial calculations.',
+        type            => 'Lists and Counts',
+        pre_calc        => 'calc_abc',
+        uses_nbr_lists  => 1,  #  how many sets of lists it must have
+        indices         => {
+            EL_ARRAY_SET1  => {
+                description    => 'Array of elements in neighbour set 1',
+                type           => 'list',
+            },
+            EL_ARRAY_SET2  => {
+                description    => 'Array of elements in neighbour set 2',
+                uses_nbr_lists => 2,
+                type           => 'list',
+            },
+            EL_ARRAY_ALL   => {
+                description    => 'Array of elements in both neighbour sets',
+                uses_nbr_lists => 2,
+                type           => 'list',
+            },
+        },
+    );
+
+    return $metadata_class->new(\%metadata);
+}
+
+sub calc_element_lists_used_as_arrays {
+    my $self = shift;
     my %args = @_;  #  rest of args into a hash
 
+    my $set1 = $args{element_list1};
+    my $set2 = $args{element_list2};
+    my $set3 = $args{element_list_all};
+
+    if ($set1 && is_hashref $set1) {
+        $set1 = [keys %$set1];
+    }
+    if ($set2 && is_hashref $set2) {
+        $set2 = [keys %$set2];
+    }
+    if ($set3 && is_hashref $set3) {
+        $set3 = [keys %$set3];
+    }
+
     my %results = (
-        EL_LIST_SET1 => $args{element_list1},
-        EL_LIST_SET2 => $args{element_list2},
-        EL_LIST_ALL  => $args{element_list_all},
+        EL_ARRAY_SET1 => $set1,
+        EL_ARRAY_SET2 => $set2,
+        EL_ARRAY_ALL  => $set3,
     );
 
     return wantarray ? %results : \%results;
@@ -1728,8 +1808,8 @@ sub _calc_abc_one_element {
         label_hash_all    => \%label_list_master,
         label_hash1       => \%label_hash1,
         label_hash2       => {},
-        element_list1     => {$element => 1},
-        element_list2     => {},
+        element_list1     => [$element],
+        element_list2     => [],
         element_list_all  => [$element],
         element_count1    => 1,
         element_count2    => 0,
@@ -1814,8 +1894,8 @@ sub _calc_abc_pairwise_mode {
         label_hash_all    => \%label_list_master,
         label_hash1       => \%label_hash1,
         label_hash2       => \%label_hash2,
-        element_list1     => {$element1 => 1},
-        element_list2     => {$element2 => 1},
+        element_list1     => [$element1],
+        element_list2     => [$element2],
         element_list_all  => [$element1, $element2],
         element_count1    => 1,
         element_count2    => 1,
@@ -2000,8 +2080,8 @@ sub _calc_abc {  #  required by all the other indices, as it gets the labels in
         label_hash_all    => \%label_list_master,
         label_hash1       => $label_list{1},
         label_hash2       => $label_list{2},
-        element_list1     => $element_check{1},
-        element_list2     => $element_check{2},
+        element_list1     => [keys %{$element_check{1}}],
+        element_list2     => [keys %{$element_check{2}}],
         element_list_all  => [keys %element_check_master],
         element_count1    => $element_count1,
         element_count2    => $element_count2,
diff --git a/lib/Biodiverse/Indices/Phylogenetic.pm b/lib/Biodiverse/Indices/Phylogenetic.pm
index 7f96b39d4..707bcdb05 100644
--- a/lib/Biodiverse/Indices/Phylogenetic.pm
+++ b/lib/Biodiverse/Indices/Phylogenetic.pm
@@ -2538,7 +2538,7 @@ sub calc_phylo_abc {
     foreach my $list_name (qw/element_list1 element_list2/) {
         $i++; #  start at 1 so we match the numbered names
         my $el_list = $args{$list_name} // next BY_LIST;
-        my @elements = keys %$el_list;
+        \my @elements = $el_list;  #  FIXME FIXME - use directly
         my $have_cache = (@elements == 1 && $cache->{$elements[0]});
         $nodes_in_path[$i]
             = (@elements == 0)
@@ -2564,9 +2564,9 @@ sub calc_phylo_abc {
         #  simplify the calcs as we only need to find $aa
         my $cache
           = $self->get_cached_value_dor_set_default_href ('_calc_phylo_abc_pairwise_branch_sum_cache');
-        my $sum_i = $cache->{(keys %{$args{element_list1}})[0]}  # use postfix deref?
+        my $sum_i = $cache->{$args{element_list1}[0]}  # use postfix deref?
             //= (sum values %list1) // 0;
-        my $sum_j = $cache->{(keys %{$args{element_list2}})[0]}
+        my $sum_j = $cache->{$args{element_list2}[0]}
             //= (sum values %list2) // 0;
         #  save some looping, mainly when there are large differences in key counts
         if (keys %list1 <= keys %list2) {
@@ -2634,15 +2634,15 @@ sub _calc_phylo_abc_lists {
         %args,
         labels   => $label_hash1,
         tree_ref => $tree,
-        el_list  => [keys %{$args{element_list1}}],
+        el_list  => $args{element_list1},
     );
 
-    my $nodes_in_path2 = scalar %{$args{element_list2}}
+    my $nodes_in_path2 = @{$args{element_list2}}
         ? $self->get_path_lengths_to_root_node (
             %args,
             labels   => $label_hash2,
             tree_ref => $tree,
-            el_list  => [keys %{$args{element_list2}}],
+            el_list  => $args{element_list2},
         )
         : {};
 
diff --git a/lib/Biodiverse/Indices/PhylogeneticRelative.pm b/lib/Biodiverse/Indices/PhylogeneticRelative.pm
index e74b5231d..009887f52 100644
--- a/lib/Biodiverse/Indices/PhylogeneticRelative.pm
+++ b/lib/Biodiverse/Indices/PhylogeneticRelative.pm
@@ -58,7 +58,6 @@ sub calc_phylo_rpd1 {
     my $total_tree_length = $tree->get_total_tree_length;
 
     my $pd_p_score = $args{PD_P};
-    my $pd_score   = $args{PD_P};
     my $label_hash = $args{PHYLO_LABELS_ON_TREE};
     my $richness   = scalar keys %$label_hash;
 
diff --git a/lib/Biodiverse/Indices/RWTurnover.pm b/lib/Biodiverse/Indices/RWTurnover.pm
index 71c47752c..ccfc9bb58 100644
--- a/lib/Biodiverse/Indices/RWTurnover.pm
+++ b/lib/Biodiverse/Indices/RWTurnover.pm
@@ -66,20 +66,12 @@ sub calc_rw_turnover {
         #  or inverse of ranges
         my $cache
             = $self->get_cached_value_dor_set_default_href ('_calc_phylo_rwt_pairwise_branch_sum_cache');
-        #  use postfix idiom?
-        #  ideally we would only be passed arrays, but see issue #919
-        my $key1 = is_hashref ($args{element_list1})
-            ? ((keys %{$args{element_list1}})[0])
-            : (${$args{element_list1}}[0]);
-        my $key2 = is_hashref ($args{element_list2})
-            ? ((keys %{$args{element_list2}})[0])
-            : (${$args{element_list2} //[]}[0]);
         #  Could use a reduce call to collapse the "sum map {} @list" idiom,
         #  thus avoiding a list generation.  These are only run once per group,
         #  though, so it might not matter.
-        my $sum_i = $cache->{$key1}
+        my $sum_i = $cache->{$args{element_list1}[0]}
             //= (sum map {1 / $_} @ranges{keys %list1}) // 0;
-        my $sum_j = $cache->{$key2}
+        my $sum_j = $cache->{$args{element_list2}[0]}
             //= (sum map {1 / $_} @ranges{keys %list2}) // 0;
         #  save some looping, mainly when there are large differences in key counts
         if (keys %list1 <= keys %list2) {
@@ -173,20 +165,12 @@ sub calc_phylo_rw_turnover {
         #  simplify the calcs as we only need to find $aa
         my $cache
             = $self->get_cached_value_dor_set_default_href ('_calc_phylo_rwt_pairwise_branch_sum_cache');
-        #  use postfix idiom?
-        #  ideally we would only be passed arrays, but see issue #919
-        my $key1 = is_hashref ($args{element_list1})
-            ? ((keys %{$args{element_list1}})[0])
-            : (${$args{element_list1}}[0]);
-        my $key2 = is_hashref ($args{element_list2})
-            ? ((keys %{$args{element_list2}})[0])
-            : (${$args{element_list2} //[]}[0]);
         #  Could use a reduce call to collapse the "sum map {} @list" idiom,
         #  thus avoiding a list generation.  These are only run once per group,
         #  though, so it might not matter.
-        my $sum_i = $cache->{$key1}
+        my $sum_i = $cache->{$args{element_list1}[0]}
             //= (sum values %list1) // 0;
-        my $sum_j = $cache->{$key2}
+        my $sum_j = $cache->{$args{element_list2}[0]}
             //= (sum values %list2) // 0;
         #  save some looping, mainly when there are large differences in key counts
         if (keys %list1 <= keys %list2) {
@@ -333,7 +317,7 @@ sub get_metadata__calc_pe_lists_per_element_set {
             set_path_length_cache_by_group_flag
             get_inverse_range_weighted_path_lengths
         /],
-        pre_calc        => ['calc_abc'],  #  don't need calc_abc2 as we don't use its counts
+        pre_calc        => [],  #  don't need calc_abc2 as we don't use its counts
         uses_nbr_lists  => 1,  #  how many lists it must have
         required_args   => {'tree_ref' => 1},
     );
@@ -358,7 +342,7 @@ sub _calc_pe_lists_per_element_set {
     foreach my $list_name (qw /element_list1 element_list2/) {
         $i++;  #  start at 1 so we match the numbered names
         my $el_list = $args{$list_name} // next BY_LIST;
-        my @elements = keys %$el_list;
+        \my @elements = $el_list;  #  FIXME
         my $have_cache = (@elements == 1 && $cache->{$elements[0]});
         $results[$i]
             = $have_cache
diff --git a/t/24-Indices-lists-and-counts.t b/t/24-Indices-lists-and-counts.t
index 6a3c80c1d..6a4b25e08 100644
--- a/t/24-Indices-lists-and-counts.t
+++ b/t/24-Indices-lists-and-counts.t
@@ -46,6 +46,7 @@ sub test_main {
             calc_nonempty_elements_used
             calc_elements_used
             calc_element_lists_used
+            calc_element_lists_used_as_arrays
             calc_abc_counts
             calc_d
             calc_local_range_lists
@@ -59,7 +60,7 @@ sub test_main {
         /],
         calc_topic_to_test => 'Lists and Counts',
         sort_array_lists   => 1,
-        #generate_result_sets => 1,
+        # generate_result_sets => 1,
     );
 }
 
@@ -116,7 +117,8 @@ done_testing;
 __DATA__
 
 @@ RESULTS_2_NBR_LISTS
-{   ABC2_LABELS_ALL => {
+{
+    ABC2_LABELS_ALL => {
         'Genus:sp1'  => 2,
         'Genus:sp10' => 1,
         'Genus:sp11' => 2,
@@ -277,19 +279,29 @@ __DATA__
     ABC_B         => 0,
     ABC_C         => 12,
     ABC_D         => 17,
-    EL_COUNT_ALL  => 5,
-    EL_COUNT_SET1 => 1,
-    EL_COUNT_SET2 => 4,
+    EL_ARRAY_ALL  => [
+        '3350000:750000', '3250000:850000',
+        '3350000:950000', '3450000:850000',
+        '3350000:850000'
+    ],
+    EL_ARRAY_SET1 => ['3350000:850000'],
+    EL_ARRAY_SET2 => [
+        '3350000:950000', '3350000:750000',
+        '3450000:850000', '3250000:850000'
+    ],
+    EL_COUNT_ALL           => 5,
     EL_COUNT_NONEMPTY_ALL  => 5,
     EL_COUNT_NONEMPTY_SET1 => 1,
     EL_COUNT_NONEMPTY_SET2 => 4,
-    EL_LIST_ALL   => [
-        '3250000:850000', '3350000:850000',
-        '3350000:750000', '3350000:950000',
-        '3450000:850000'
+    EL_COUNT_SET1          => 1,
+    EL_COUNT_SET2          => 4,
+    EL_LIST_ALL            => [
+        '3350000:750000', '3250000:850000',
+        '3350000:950000', '3450000:850000',
+        '3350000:850000'
     ],
-    EL_LIST_SET1 => { '3350000:850000' => 1 },
-    EL_LIST_SET2 => {
+    EL_LIST_SET1           => { '3350000:850000' => 1 },
+    EL_LIST_SET2           => {
         '3250000:850000' => 1,
         '3350000:750000' => 1,
         '3350000:950000' => 1,
@@ -317,7 +329,7 @@ __DATA__
     RICHNESS_ALL    => 14,
     RICHNESS_SET1   => 2,
     RICHNESS_SET2   => 14
-}
+};
 
 
 @@ RESULTS_1_NBR_LISTS
@@ -356,15 +368,16 @@ __DATA__
         Q095 => 4,
         Q100 => 4
     },
-    ABC3_SD_SET1         => '1.4142135623731',
-    ABC3_SUM_SET1        => 6,
-    ABC_D                => 29,
-    EL_COUNT_SET1        => 1,
-    EL_COUNT_ALL         => 1,
+    ABC3_SD_SET1           => '1.4142135623731',
+    ABC3_SUM_SET1          => 6,
+    ABC_D                  => 29,
+    EL_ARRAY_SET1          => ['3350000:850000'],
+    EL_COUNT_ALL           => 1,
     EL_COUNT_NONEMPTY_ALL  => 1,
     EL_COUNT_NONEMPTY_SET1 => 1,
-    EL_LIST_SET1         => { '3350000:850000' => 1 },
-    LABEL_COUNT_RANK_PCT => {
+    EL_COUNT_SET1          => 1,
+    EL_LIST_SET1           => { '3350000:850000' => 1 },
+    LABEL_COUNT_RANK_PCT   => {
         'Genus:sp20' => undef,
         'Genus:sp26' => undef
     },