diff --git a/lib/liquid/tags/for.rb b/lib/liquid/tags/for.rb
index 8d2b27b..47e67d1 100644
--- a/lib/liquid/tags/for.rb
+++ b/lib/liquid/tags/for.rb
@@ -1,6 +1,6 @@
 module Liquid
 
-  # "For" iterates over an array or collection. 
+  # "For" iterates over an array or collection.
   # Several useful variables are available to you within the loop.
   #
   # == Basic usage:
@@ -22,7 +22,7 @@ module Liquid
   #
   #    {% for item in collection limit:5 offset:10 %}
   #      {{ item.name }}
-  #    {% end %}             
+  #    {% end %}
   #
   #  To reverse the for loop simply use {% for item in collection reversed %}
   #
@@ -31,7 +31,7 @@ module Liquid
   # forloop.name:: 'item-collection'
   # forloop.length:: Length of the loop
   # forloop.index:: The current item's position in the collection;
-  #                 forloop.index starts at 1. 
+  #                 forloop.index starts at 1.
   #                 This is helpful for non-programmers who start believe
   #                 the first item in an array is 1, not 0.
   # forloop.index0:: The current item's position in the collection
@@ -43,19 +43,19 @@ module Liquid
   # forloop.first:: Returns true if the item is the first item.
   # forloop.last:: Returns true if the item is the last item.
   #
-  class For < Block                                             
-    Syntax = /(\w+)\s+in\s+(#{QuotedFragment}+)\s*(reversed)?/o
-  
+  class For < Block
+    Syntax = /\A(\w+)\s+in\s+(#{QuotedFragment}+)\s*(reversed)?/o
+
     def initialize(tag_name, markup, tokens)
       if markup =~ Syntax
         @variable_name = $1
         @collection_name = $2
-        @name = "#{$1}-#{$2}"           
-        @reversed = $3             
+        @name = "#{$1}-#{$2}"
+        @reversed = $3
         @attributes = {}
         markup.scan(TagAttributes) do |key, value|
           @attributes[key] = value
-        end        
+        end
       else
         raise SyntaxError.new("Syntax Error in 'for loop' - Valid syntax: for [item] in [collection]")
       end
@@ -68,51 +68,51 @@ module Liquid
       return super unless tag == 'else'
       @nodelist = @else_block = []
     end
-  
-    def render(context)       
+
+    def render(context)
       context.registers[:for] ||= Hash.new(0)
-    
+
       collection = context[@collection_name]
       collection = collection.to_a if collection.is_a?(Range)
-    
+
       # Maintains Ruby 1.8.7 String#each behaviour on 1.9
       return render_else(context) unless iterable?(collection)
-                                                 
+
       from = if @attributes['offset'] == 'continue'
         context.registers[:for][@name].to_i
       else
         context[@attributes['offset']].to_i
       end
-        
+
       limit = context[@attributes['limit']]
-      to    = limit ? limit.to_i + from : nil  
+      to    = limit ? limit.to_i + from : nil
 
 
       segment = Utils.slice_collection_using_each(collection, from, to)
 
       return render_else(context) if segment.empty?
-      
+
       segment.reverse! if @reversed
 
       result = ''
-        
-      length = segment.length            
-            
+
+      length = segment.length
+
       # Store our progress through the collection for the continue flag
       context.registers[:for][@name] = from + segment.length
-              
+
       context.stack do
         segment.each_with_index do |item, index|
           context[@variable_name] = item
           context['forloop'] = {
             'name'    => @name,
             'length'  => length,
-            'index'   => index + 1, 
-            'index0'  => index, 
+            'index'   => index + 1,
+            'index0'  => index,
             'rindex'  => length - index,
             'rindex0' => length - index - 1,
             'first'   => (index == 0),
-            'last'    => (index == length - 1) }
+          'last'    => (index == length - 1) }
 
           result << render_all(@for_block, context)
 
@@ -124,8 +124,8 @@ module Liquid
           end
         end
       end
-      result     
-    end          
+      result
+    end
 
     private
 
diff --git a/test/liquid/tags/for_tag_test.rb b/test/liquid/tags/for_tag_test.rb
index edfdc88..6a0e55d 100644
--- a/test/liquid/tags/for_tag_test.rb
+++ b/test/liquid/tags/for_tag_test.rb
@@ -281,4 +281,10 @@ HERE
   def test_blank_string_not_iterable
     assert_template_result('', "{% for char in characters %}I WILL NOT BE OUTPUT{% endfor %}", 'characters' => '')
   end
+
+  def test_bad_variable_naming_in_for_loop
+    assert_raise(Liquid::SyntaxError) do
+      Liquid::Template.parse('{% for a/b in x %}{% endfor %}')
+    end
+  end
 end