diff --git a/build-languages.js b/build-languages.js
index 53a9d3b7..26e31364 100644
--- a/build-languages.js
+++ b/build-languages.js
@@ -67,6 +67,10 @@ class BuildLanguages {
         if (k in translationsStrings[l]) {
           throw new Error(`Duplicate translation for key ${k} in lang ${l}.`)
         }
+        if ((typeof v) !== 'string') {
+          // ignoring untranslated strings.
+          continue
+        }
         translationsStrings[l][k] = v
       }
     }
@@ -90,6 +94,10 @@ class BuildLanguages {
         if (!(k in reference)) {
           throw new Error(`File ${filePath} contains unknown keys. Key=${k}.`)
         }
+        if ((typeof o[k]) !== 'string') {
+          // ignoring untranslated strings.
+          continue
+        }
         const newKey = reference[k]
         this.translationsStrings[l][newKey] = o[k]
       }