diff --git a/web/phonagen.js b/web/phonagen.js
index 0894a6a..2b0493f 100644
--- a/web/phonagen.js
+++ b/web/phonagen.js
@@ -121,9 +121,8 @@ phonagen.formatWord = function (phonemes, phonology) {
   for (var writing of phonology.transcriptions) {
     var word = ""
     for (var id of phonemes) {
-      var letter = phonology.entries.get(id)[writing]
-      if (typeof letter !== "undefined") {
-        word += letter
+      if (phonology.entries.has(id)) {
+        word += phonology.entries.get(id)[writing]
       }
     }
     wordTranscriptions.set(writing, word)