diff --git a/src/cpp/phonemize.hpp b/src/cpp/phonemize.hpp
index 80e166d..cb9eaf0 100644
--- a/src/cpp/phonemize.hpp
+++ b/src/cpp/phonemize.hpp
@@ -126,6 +126,10 @@ void phonemes2ids(vector<Phoneme> &phonemes, PhonemizeConfig &phonemizeConfig,
           phonemeIds.push_back(phonemizeConfig.idPad);
         }
       }
+    } else {
+      string phonemeStr;
+      utf8::append(*phoneme, phonemeStr);
+      cerr << "[WARN] No id for phoneme: " << phonemeStr << endl;
     }
   }