diff --git a/lib/nested_has_many_through/association.rb b/lib/nested_has_many_through/association.rb
index 9cb3b06..9ddfca8 100644
--- a/lib/nested_has_many_through/association.rb
+++ b/lib/nested_has_many_through/association.rb
@@ -98,7 +98,7 @@ def construct_has_many_or_belongs_to_attributes(reflection, association_class, t
       # Add type_condition, if applicable
       conditions += " AND #{association_class.send(:type_condition).to_sql}" if association_class.finder_needs_type_condition?
       # Add custom conditions
-      conditions += " AND (#{association_class.send(:sanitize_sql, reflection.options[:conditions])})" if reflection.options[:conditions]
+      conditions += " AND (#{interpolate_and_sanitize_sql(reflection.options[:conditions], nil, association_class)})" if reflection.options[:conditions]
 
       if reflection.macro == :belongs_to
         if reflection.options[:polymorphic]
diff --git a/spec/rails_app/app/models/author.rb b/spec/rails_app/app/models/author.rb
index f56c0c1..e07c4db 100644
--- a/spec/rails_app/app/models/author.rb
+++ b/spec/rails_app/app/models/author.rb
@@ -1,5 +1,5 @@
 class Author < User
-  has_many :posts
+  has_many :posts, :conditions => proc{ "1=1" }
   has_many :sources
   has_many :categories, :through => :posts
   has_many :similar_posts, :through => :categories, :source => :posts