diff --git a/lib/bio/appl/fasta.rb b/lib/bio/appl/fasta.rb
index e3f033851..e2e4e37d7 100644
--- a/lib/bio/appl/fasta.rb
+++ b/lib/bio/appl/fasta.rb
@@ -66,6 +66,15 @@ def format=(num)
   end
   attr_reader :format
 
+  # OBSOLETE. Does nothing and shows warning messages.
+  #
+  # Historically, selecting parser to use ('format6' or 'format10' were
+  # expected, but only 'format10' was available as a working parser).
+  #
+  def self.parser(parser)
+    warn 'Bio::Fasta.parser is obsoleted and will soon be removed.'
+  end
+
   # Returns a FASTA factory object (Bio::Fasta) to run FASTA search on
   # local computer.
   def self.local(program, db, option = '')
diff --git a/lib/bio/appl/fasta/format10.rb b/lib/bio/appl/fasta/format10.rb
index 4c752e6db..ae140fb6e 100644
--- a/lib/bio/appl/fasta/format10.rb
+++ b/lib/bio/appl/fasta/format10.rb
@@ -8,6 +8,7 @@
 #
 
 require 'bio/appl/fasta'
+require 'bio/io/flatfile/splitter'
 
 module Bio
 class Fasta