Like usage in sql sentence

Question

hey guys..i dont know where is my mistake in my sql sentence..i cant get the result when i give the variable..but it works fine without Like word..but it doesnt give the result what i need...here is my proc
ALTER procedure [dbo].[sp_SearchFirm]
(
@aranan_firma nvarchar(50)
)
as
Begin
Select firma_adi From Firmalar Where firma_adi LIKE '%@aranan_firma%'
End