EXHIBIT A
JOINT FILING AGREEMENT
The undersigned agree that this Ninth Amendment dated December 16, 2009, relating to Argyle Security, Inc., shall be filed on behalf of the undersigned.
         
  MEZZANINE MANAGEMENT FUND IV A, L.P.
 
 
  By:   /s/ Christopher C. Morris  
    Name:   Christopher C. Morris   
    Title:   Authorized Signatory   
 
  MEZZANINE MANAGEMENT FUND IV COINVEST A, L.P.
 
 
  By:   /s/ Christopher C. Morris  
    Name:   Christopher C. Morris   
    Title:   Authorized Signatory   
 
  MEZZANINE MANAGEMENT LIMITED
 
 
  By:   /s/ Christopher C. Morris  
    Name:   Christopher C. Morris   
    Title:   Authorized Signatory