diff --git a/lib/pg_query/treewalker.rb b/lib/pg_query/treewalker.rb
index 79848b08..19f0253b 100644
--- a/lib/pg_query/treewalker.rb
+++ b/lib/pg_query/treewalker.rb
@@ -20,13 +20,18 @@ def treewalker!(tree) # rubocop:disable Metrics/CyclomaticComplexity
             node = parent_node[parent_field.to_s]
             next if node.nil?
             location = parent_location + [parent_field]
-
             yield(parent_node, parent_field, node, location) if node.is_a?(Google::Protobuf::MessageExts) || node.is_a?(Google::Protobuf::RepeatedField)
 
             nodes << [node, location] unless node.nil?
           end
         when Google::Protobuf::RepeatedField
-          nodes += parent_node.map.with_index { |e, idx| [e, parent_location + [idx]] }
+          parent_node.each_with_index do |node, parent_field|
+            next if node.nil?
+            location = parent_location + [parent_field]
+            yield(parent_node, parent_field, node, location) if node.is_a?(Google::Protobuf::MessageExts) || node.is_a?(Google::Protobuf::RepeatedField)
+
+            nodes << [node, location] unless node.nil?
+          end
         end
 
         break if nodes.empty?
diff --git a/spec/lib/treewalker_spec.rb b/spec/lib/treewalker_spec.rb
new file mode 100644
index 00000000..b8ef7788
--- /dev/null
+++ b/spec/lib/treewalker_spec.rb
@@ -0,0 +1,36 @@
+require 'spec_helper'
+
+describe PgQuery, '.treewalker' do
+  it 'walks nodes contained in repeated fields' do
+    locations = []
+    described_class.parse("SELECT to_timestamp($1)").walk! do |_, _, _, location|
+      locations << location
+    end
+    expect(locations).to match_array [
+      [:stmts],
+      [:stmts, 0],
+      [:stmts, 0, :stmt],
+      [:stmts, 0, :stmt, :select_stmt],
+      [:stmts, 0, :stmt, :select_stmt, :distinct_clause],
+      [:stmts, 0, :stmt, :select_stmt, :target_list],
+      [:stmts, 0, :stmt, :select_stmt, :from_clause],
+      [:stmts, 0, :stmt, :select_stmt, :group_clause],
+      [:stmts, 0, :stmt, :select_stmt, :window_clause],
+      [:stmts, 0, :stmt, :select_stmt, :values_lists],
+      [:stmts, 0, :stmt, :select_stmt, :sort_clause],
+      [:stmts, 0, :stmt, :select_stmt, :locking_clause],
+      [:stmts, 0, :stmt, :select_stmt, :target_list, 0],
+      [:stmts, 0, :stmt, :select_stmt, :target_list, 0, :res_target],
+      [:stmts, 0, :stmt, :select_stmt, :target_list, 0, :res_target, :indirection],
+      [:stmts, 0, :stmt, :select_stmt, :target_list, 0, :res_target, :val],
+      [:stmts, 0, :stmt, :select_stmt, :target_list, 0, :res_target, :val, :func_call],
+      [:stmts, 0, :stmt, :select_stmt, :target_list, 0, :res_target, :val, :func_call, :funcname],
+      [:stmts, 0, :stmt, :select_stmt, :target_list, 0, :res_target, :val, :func_call, :args],
+      [:stmts, 0, :stmt, :select_stmt, :target_list, 0, :res_target, :val, :func_call, :agg_order],
+      [:stmts, 0, :stmt, :select_stmt, :target_list, 0, :res_target, :val, :func_call, :funcname, 0],
+      [:stmts, 0, :stmt, :select_stmt, :target_list, 0, :res_target, :val, :func_call, :args, 0],
+      [:stmts, 0, :stmt, :select_stmt, :target_list, 0, :res_target, :val, :func_call, :funcname, 0, :string],
+      [:stmts, 0, :stmt, :select_stmt, :target_list, 0, :res_target, :val, :func_call, :args, 0, :param_ref]
+    ]
+  end
+end