diff --git a/lib/jekyll-pandoc-multiple-formats/generator.rb b/lib/jekyll-pandoc-multiple-formats/generator.rb
index 5a57b2c91fe4a1ee5211a5932fb97c357b310362..a8174ea7ebd284893b12ca4b1b2792c85ead9940 100644
--- a/lib/jekyll-pandoc-multiple-formats/generator.rb
+++ b/lib/jekyll-pandoc-multiple-formats/generator.rb
@@ -50,6 +50,13 @@ class PandocGenerator < Generator
       @site.post_attr_hash('categories').each_pair do |title, posts|
         posts.sort!
         pandoc_file = PandocFile.new(@site, output, posts, title)
+
+        if @site.keep_files.include? pandoc_file.relative_path
+          puts "#{pandoc_file.relative_path} is a category file AND a post file"
+          puts 'change the category name to fix this'
+          next
+        end
+
         next unless pandoc_file.write
 
         @site.keep_files << pandoc_file.relative_path
diff --git a/lib/jekyll-pandoc-multiple-formats/imposition.rb b/lib/jekyll-pandoc-multiple-formats/imposition.rb
index 7326aaadc3e0c9db0e724d1108c322cb64cd0943..4289420418d1a1b7dcfc4b9f17c3e61eedf6dbdd 100644
--- a/lib/jekyll-pandoc-multiple-formats/imposition.rb
+++ b/lib/jekyll-pandoc-multiple-formats/imposition.rb
@@ -68,7 +68,7 @@ module JekyllPandocMultipleFormats
         # Split in halves
         # [ [ 1, 2, 3, 4, 5, 6, 7, 8 ],
         #   [ 9, 10, 11, 12, 13, 14, '{}', '{}' ] ]
-        halved = fold.each_slice(@signature / 2).to_a
+        halved = fold.each_slice(fold.size / 2).to_a
         # Add a nil as last page.  When we reverse it and intercalate by
         # two pages, we'll have [nil, last_page] instead of
         # [last_page,second_to_last_page]
diff --git a/lib/jekyll-pandoc-multiple-formats/pandoc_file.rb b/lib/jekyll-pandoc-multiple-formats/pandoc_file.rb
index aa8b881d52d4605c84e6948e12b876003f1147fa..14b698f1ef53849a8d9522eae169eeca77f69538 100644
--- a/lib/jekyll-pandoc-multiple-formats/pandoc_file.rb
+++ b/lib/jekyll-pandoc-multiple-formats/pandoc_file.rb
@@ -41,12 +41,12 @@ module Jekyll
         raise ArgumentError.new "'title' argument is required for multipost file" unless title
 
         @title = title
-        @slug  = Utils.slugify(title)
       else
         @posts = [posts]
-        @slug  = posts.data['slug']
         @title = posts.data['title'] unless title
       end
+
+      @slug  = Utils.slugify(title)
     end
 
     def path
@@ -185,13 +185,11 @@ module Jekyll
 
     def pdf_cover!
       if has_cover? && !File.exists?(pdf_cover)
-        Dir::chdir(@site.config['source']) do
-          Open3::popen3("convert \"#{cover}\" \"#{pdf_cover}\"") do |stdin, stdout, stderr, thread|
-            STDERR.print stderr.read
+        Open3::popen3("convert \"#{cover}\" \"#{pdf_cover}\"") do |stdin, stdout, stderr, thread|
+          STDERR.print stderr.read
 
-            # Wait for the process to finish
-            thread.value
-          end
+          # Wait for the process to finish
+          thread.value
         end
       end
 
diff --git a/lib/jekyll-pandoc-multiple-formats/version.rb b/lib/jekyll-pandoc-multiple-formats/version.rb
index f06162dead1d74a753522add3d2800bb3cc7574e..a49a69c4aae289d421f7c54e79fc03ce32d5c2fc 100644
--- a/lib/jekyll-pandoc-multiple-formats/version.rb
+++ b/lib/jekyll-pandoc-multiple-formats/version.rb
@@ -1,3 +1,3 @@
 module JekyllPandocMultipleFormats
-  VERSION = '0.2.6'
+  VERSION = '0.2.7'
 end