diff --git a/faster_whisper/transcribe.py b/faster_whisper/transcribe.py
index bab6d44..911928f 100644
--- a/faster_whisper/transcribe.py
+++ b/faster_whisper/transcribe.py
@@ -68,9 +68,10 @@ class WhisperModel:
         """Initializes the Whisper model.
 
         Args:
-          model_size_or_path: Size of the model to use (e.g. "large-v2", "small", "tiny.en", etc.)
-            or a path to a converted model directory. When a size is configured, the converted
-            model is downloaded from the Hugging Face Hub.
+          model_size_or_path: Size of the model to use (tiny, tiny.en, base, base.en,
+            small, small.en, medium, medium.en, or large-v2) or a path to a converted
+            model directory. When a size is configured, the converted model is downloaded
+            from the Hugging Face Hub.
           device: Device to use for computation ("cpu", "cuda", "auto").
           device_index: Device ID to use.
             The model can also be loaded on multiple GPUs by passing a list of IDs
diff --git a/faster_whisper/utils.py b/faster_whisper/utils.py
index bfd2f17..b97c9a1 100644
--- a/faster_whisper/utils.py
+++ b/faster_whisper/utils.py
@@ -4,6 +4,18 @@ import huggingface_hub
 
 from tqdm.auto import tqdm
 
+_MODELS = (
+    "tiny.en",
+    "tiny",
+    "base.en",
+    "base",
+    "small.en",
+    "small",
+    "medium.en",
+    "medium",
+    "large-v2",
+)
+
 
 def download_model(
     size: str,
@@ -23,7 +35,15 @@ def download_model(
 
     Returns:
       The path to the downloaded model.
+
+    Raises:
+      ValueError: if the model size is invalid.
     """
+    if size not in _MODELS:
+        raise ValueError(
+            "Invalid model size '%s', expected one of: %s" % (size, ", ".join(_MODELS))
+        )
+
     repo_id = "guillaumekln/faster-whisper-%s" % size
     kwargs = {}