diff --git a/lib/lenjador/preprocessors/strategies/mask.rb b/lib/lenjador/preprocessors/strategies/mask.rb
index 23221d3..9217d2f 100644
--- a/lib/lenjador/preprocessors/strategies/mask.rb
+++ b/lib/lenjador/preprocessors/strategies/mask.rb
@@ -21,8 +21,11 @@ def process(data, pointer = '')
           when Array
             process_array(data, pointer)
 
-          else
+          when String, Numeric, Symbol, Date, Time, TrueClass, FalseClass, NilClass
             data
+
+          else
+            MASKED_VALUE
           end
         end
 
diff --git a/lib/lenjador/preprocessors/strategies/prune.rb b/lib/lenjador/preprocessors/strategies/prune.rb
index ab65380..deeb331 100644
--- a/lib/lenjador/preprocessors/strategies/prune.rb
+++ b/lib/lenjador/preprocessors/strategies/prune.rb
@@ -18,8 +18,11 @@ def process(data, pointer = '')
           when Array
             process_array(data, pointer)
 
-          else
+          when String, Numeric, Symbol, Date, Time, TrueClass, FalseClass, NilClass
             data
+
+          else
+            nil
           end
         end