diff --git a/phsource/ph_vietnam b/phsource/ph_vietnam
index a7f77120..c6dfb9af 100644
--- a/phsource/ph_vietnam
+++ b/phsource/ph_vietnam
@@ -62,7 +62,7 @@ phoneme a
 	IF nextPh(N) OR nextPh(c) THEN
 	FMT(vnasal/a_n)
 	ELSE
-	FMT(vowel/a_4)  //a_4)
+	FMT(vietnam/a)  //a_4)
 	ENDIF
 endphoneme