diff --git a/lib/has_calendar.rb b/lib/has_calendar.rb
index 15e52b7..56cfdae 100644
--- a/lib/has_calendar.rb
+++ b/lib/has_calendar.rb
@@ -12,19 +12,19 @@ def calendar(options={}, &block)
           :caption_format => :default,
           :id => "calendar"
         }.merge(options)
-      
+
         cmd = 'cal '
         cmd << '-m ' unless RUBY_PLATFORM =~ /darwin/
-      
+
         # execute the command
         output = IO.popen("#{cmd} #{options[:month]} #{options[:year]}") {|f| f.read}
-      
+
         # get calendar lines
         io = StringIO.new(output)
         lines = io.readlines
         lines = lines[2, lines.size-2]
         lines.map!(&:chomp)
-      
+
         # strip spaces from each day and group them
         days = lines.inject([]) do |holder, line|
           0.step(line.size, 3) do |n|
@@ -32,34 +32,37 @@ def calendar(options={}, &block)
           end
           holder
         end
-        
+
         # group all records if data is provided
         if options[:events]
           records = options[:events].inject({}) do |memo, record|
-            unless record.send(options[:field]).nil?
-              stamp = record.send(options[:field]).to_date.to_s(:number)
+            field = record.send(options[:field])
+
+            if field
+              stamp = field.to_date.to_s(:number)
               memo[stamp] ||= []
               memo[stamp] << record
-            end  
-	    memo
-	  end
+            end
+
+            memo
+          end
         end
-      
+
         # building the calendar
         contents = content_tag(:table, :id => options[:id], :class => 'calendar') do
           # first, get the header
           today = Date.today
           date = today.beginning_of_week
           date = date - 1.day if RUBY_PLATFORM =~ /darwin/
-        
+
           caption = content_tag(:caption, l(Date.new(options[:year], options[:month]), :format => options[:caption_format]))
-        
+
           head = content_tag(:thead) do
             content_tag(:tr) do
               (0..6).collect { |i| content_tag(:th, l(date + i.days, :format => options[:header_format])) } * ""
             end
           end
-        
+
           # then get the body
           rows = ""
           days.in_groups_of(7, "") do |group|
@@ -69,23 +72,23 @@ def calendar(options={}, &block)
               group.inject("") do |cols, day|
                 col_options = {:class => 'day'}
                 events = ""
-              
+
                 unless day.blank?
                   date = Date.new(options[:year], options[:month], day.to_i)
                   col_options[:class] << ' today' if today == date
                   col_options[:class] << ' weekend' if [0,6].include?(date.wday)
                 end
-              
+
                 if block_given? && !day.blank?
                   if options[:events]
                     events = capture(date, records[date.to_s(:number)], &block)
                   else
                     events = capture(date, &block)
                   end
-                  
+
                   col_options[:class] << ' events' unless events.blank?
                 end
-              
+
                 cols << content_tag(:td, col_options) do
                   day = options[:today] if options[:today] && date == today
                   span = content_tag(:span, day)
@@ -94,12 +97,12 @@ def calendar(options={}, &block)
               end
             end
           end
-        
+
           caption + head + rows
         end
-      
-        concat(contents) if block_given?        
-        
+
+        concat(contents) if block_given?
+
         contents
       end
     end