diff --git a/phsource/ph_vietnam b/phsource/ph_vietnam
index 04242b62..35a63c8a 100644
--- a/phsource/ph_vietnam
+++ b/phsource/ph_vietnam
@@ -708,7 +708,7 @@ phoneme N // si**ng**
   vcd lbv nas
   Vowelout f1=3 f2=2300 300 400  f3=-200 80  len=40 rms=20 brk
   lengthmod 12            // longer than 'n'
-  
+  length 163
   FMT(n/nm)
 endphoneme