diff --git a/net/net-lib.pl b/net/net-lib.pl
index a30f82cbf..6e9786fe8 100644
--- a/net/net-lib.pl
+++ b/net/net-lib.pl
@@ -147,7 +147,7 @@ sub prefix_to_mask
 {
 return $_[0] >= 24 ? "255.255.255.".(256-(2 ** (32-$_[0]))) :
        $_[0] >= 16 ? "255.255.".(256-(2 ** (24-$_[0]))).".0" :
-       $_[0] >= 16 ? "255.".(256-(2 ** (16-$_[0]))).".0.0" :
+       $_[0] >= 8 ? "255.".(256-(2 ** (16-$_[0]))).".0.0" :
 		     (256-(2 ** (8-$_[0]))).".0.0.0";
 }