diff --git a/TTS/vocoder/datasets/preprocess.py b/TTS/vocoder/datasets/preprocess.py
index d8cc350a..0f69b812 100644
--- a/TTS/vocoder/datasets/preprocess.py
+++ b/TTS/vocoder/datasets/preprocess.py
@@ -33,8 +33,8 @@ def preprocess_wav_files(out_path: str, config: Coqpit, ap: AudioProcessor):
             np.save(quant_path, quant)
 
 
-def find_wav_files(data_path):
-    wav_paths = glob.glob(os.path.join(data_path, "**", "*.wav"), recursive=True)
+def find_wav_files(data_path, file_ext="wav"):
+    wav_paths = glob.glob(os.path.join(data_path, "**", f"*.{file_ext}"), recursive=True)
     return wav_paths
 
 
@@ -43,8 +43,9 @@ def find_feat_files(data_path):
     return feat_paths
 
 
-def load_wav_data(data_path, eval_split_size):
-    wav_paths = find_wav_files(data_path)
+def load_wav_data(data_path, eval_split_size, file_ext="wav"):
+    wav_paths = find_wav_files(data_path, file_ext=file_ext)
+    assert len(wav_paths) > 0, f" [!] {data_path} is empty."
     np.random.seed(0)
     np.random.shuffle(wav_paths)
     return wav_paths[:eval_split_size], wav_paths[eval_split_size:]