diff --git a/lib/jekyll/convertible.rb b/lib/jekyll/convertible.rb
index d587f8f3..2186d95c 100644
--- a/lib/jekyll/convertible.rb
+++ b/lib/jekyll/convertible.rb
@@ -56,6 +56,10 @@ module Jekyll
       end
 
       self.data ||= {}
+
+      unless self.data.is_a?(Hash)
+        Jekyll.logger.abort_with "Fatal:", "Invalid YAML front matter in #{File.join(base, name)}"
+      end
     end
 
     # Transform the contents based on the content type.