diff --git a/lib/mongoid/contextual/mongo.rb b/lib/mongoid/contextual/mongo.rb
index <HASH>..<HASH> 100644
--- a/lib/mongoid/contextual/mongo.rb
+++ b/lib/mongoid/contextual/mongo.rb
@@ -337,7 +337,7 @@ module Mongoid
       # @since 3.1.0
       def pluck(field)
         normalized = klass.database_field_name(field)
-        query.select(normalized => 1).map{ |doc| doc[normalized] }.compact
+        query.dup.select(normalized => 1).map{ |doc| doc[normalized] }.compact
       end
 
       # Skips the provided number of documents.
dup the query so the existing query is not modified