diff --git a/README.md b/README.md
index b6a6d9e..378a158 100644
--- a/README.md
+++ b/README.md
@@ -83,6 +83,8 @@ Create a `Cardfile` in your working directory. It should look something like thi
 @session.configure do |c|
   # manipulate the data after reading from the spreadsheet
   # c.post_read_data = proc { |data|
+  #  data[:active_layers] << "My Cool Layer"
+  #  data[:active_layers] << /a regular expression/i
   #  data[:replacements]['Superpower Text'] << '!!'
   # }
 
diff --git a/lib/svggvs/session.rb b/lib/svggvs/session.rb
index ecb25d1..148f082 100644
--- a/lib/svggvs/session.rb
+++ b/lib/svggvs/session.rb
@@ -55,6 +55,27 @@ module SVGGVS
       card_finished!
     end
 
+    class ActiveLayerMatcher < SimpleDelegator
+      def initialize(layers)
+        @layers = layers
+      end
+
+      def __getobj__
+        @layers
+      end
+
+      def include?(name)
+        @layers.any? { |layer|
+          case layer
+          when Regexp
+            layer =~ name
+          else
+            layer == name
+          end
+        }
+      end
+    end
+
     def data_source=(source)
       data_source = DataSource.new(source)
 
@@ -68,7 +89,7 @@ module SVGGVS
 
           with_new_target do |target|
             target.inject!
-            target.active_layers = card[:active_layers]
+            target.active_layers = ActiveLayerMatcher.new(card[:active_layers])
             target.replacements = card[:replacements]
           end
         end