diff --git a/lib/detectmsk40.f90 b/lib/detectmsk40.f90
index d8489e860..0827126ab 100644
--- a/lib/detectmsk40.f90
+++ b/lib/detectmsk40.f90
@@ -355,10 +355,7 @@ subroutine detectmsk40(cbig,n,pchk_file,mycall,hiscall,lines,nmessages,   &
               softbits=softbits/ssig
 
               sigma=0.75
-!              if(xsnr.lt.-2.0 ) sigma=0.8
-!              if(xsnr.lt.-3.0 ) sigma=0.95
-!              if(xsnr.lt.-4.0 ) sigma=1.1
-              if(xsnr.lt.1.5) sigma=1.1 - 0.14*(xsnr+4.0) 
+              if(xsnr.lt.1.5) sigma=1.1 - 0.0875*(xsnr+4.0) 
               lratio(1:32)=exp(2.0*softbits(9:40)/(sigma*sigma))
 
               max_iterations=5