diff --git a/lib/arel/visitors/to_sql.rb b/lib/arel/visitors/to_sql.rb
index f52ce101c056dc0ded4b67733fafdc8e75b2b9a9..1412797fb5f095a064130b85267ea610beb23901 100644
--- a/lib/arel/visitors/to_sql.rb
+++ b/lib/arel/visitors/to_sql.rb
@@ -277,6 +277,7 @@ def visit_String o; quote(o, @last_column) end
       alias :visit_Symbol :visit_String
       alias :visit_Time :visit_String
       alias :visit_TrueClass :visit_String
+      alias :visit_NilClass :visit_String
 
       def quote value, column = nil
         @connection.quote value, column
diff --git a/test/visitors/test_to_sql.rb b/test/visitors/test_to_sql.rb
index d7cf71961a29b38cad942900ab0e192de9fa5b46..a6042ef9c3654cea045d33356155ec9505778549 100644
--- a/test/visitors/test_to_sql.rb
+++ b/test/visitors/test_to_sql.rb
@@ -45,6 +45,10 @@ module Visitors
         @visitor.accept Date.today
       end
 
+      it "should visit_NilClass" do
+        @visitor.accept(nil).must_be_like "NULL"
+      end
+
       it "should visit_Arel_Nodes_And" do
         node = Nodes::And.new @attr.eq(10), @attr.eq(11)
         @visitor.accept(node).must_be_like %{