diff --git a/lib/nanoc/base/entities/processing_actions/snapshot.rb b/lib/nanoc/base/entities/processing_actions/snapshot.rb
index 40cec9d098..0a4ac092ea 100644
--- a/lib/nanoc/base/entities/processing_actions/snapshot.rb
+++ b/lib/nanoc/base/entities/processing_actions/snapshot.rb
@@ -21,9 +21,9 @@ def serialize
 
     NONE = Object.new
 
-    contract String => self
-    def add_path(path)
-      self.class.new(@snapshot_names, @paths + [path])
+    contract C::KeywordArgs[snapshot_names: C::Optional[C::IterOf[Symbol]], paths: C::Optional[C::IterOf[String]]] => self
+    def update(snapshot_names: [], paths: [])
+      self.class.new(@snapshot_names + snapshot_names, @paths + paths)
     end
 
     contract C::None => String
diff --git a/lib/nanoc/rule_dsl/rule_memory_calculator.rb b/lib/nanoc/rule_dsl/rule_memory_calculator.rb
index ccb4a0424a..7496704599 100644
--- a/lib/nanoc/rule_dsl/rule_memory_calculator.rb
+++ b/lib/nanoc/rule_dsl/rule_memory_calculator.rb
@@ -136,7 +136,7 @@ def copy_path_from_routing_rule(action, rep:)
 
       path_from_rules = paths_from_rules.find(&:itself)
       if path_from_rules
-        action.add_path(path_from_rules.to_s)
+        action.update(paths: [path_from_rules.to_s])
       else
         action
       end
diff --git a/spec/nanoc/base/entities/processing_actions/snapshot_spec.rb b/spec/nanoc/base/entities/processing_actions/snapshot_spec.rb
index a7fbb11863..d3fbe050ed 100644
--- a/spec/nanoc/base/entities/processing_actions/snapshot_spec.rb
+++ b/spec/nanoc/base/entities/processing_actions/snapshot_spec.rb
@@ -16,9 +16,23 @@
     it { is_expected.to eql('<Nanoc::Int::ProcessingActions::Snapshot [:before_layout], true, ["/foo.md"]>') }
   end
 
-  describe '#add_path' do
-    subject { action.add_path('/donkey.md') }
-    its(:snapshot_names) { is_expected.to eql([:before_layout]) }
-    its(:paths) { is_expected.to eql(['/foo.md', '/donkey.md']) }
+  describe '#update' do
+    context 'with nothing' do
+      subject { action.update }
+      its(:snapshot_names) { is_expected.to eql([:before_layout]) }
+      its(:paths) { is_expected.to eql(['/foo.md']) }
+    end
+
+    context 'with snapshot name' do
+      subject { action.update(snapshot_names: [:zebra]) }
+      its(:snapshot_names) { is_expected.to eql([:before_layout, :zebra]) }
+      its(:paths) { is_expected.to eql(['/foo.md']) }
+    end
+
+    context 'with paths' do
+      subject { action.update(paths: ['/donkey.md', '/giraffe.md']) }
+      its(:snapshot_names) { is_expected.to eql([:before_layout]) }
+      its(:paths) { is_expected.to eql(['/foo.md', '/donkey.md', '/giraffe.md']) }
+    end
   end
 end