diff --git a/deepinfra/utils/read_stream.py b/deepinfra/utils/read_stream.py
index 1c2a3c1..81de154 100644
--- a/deepinfra/utils/read_stream.py
+++ b/deepinfra/utils/read_stream.py
@@ -3,6 +3,14 @@
 
 import httpx
 
+from deepinfra._exceptions import (
+    APIConnectionError,
+    APIStatusError,
+    APITimeoutError,
+)
+
+DOWNLOAD_TIMEOUT = 30.0
+
 
 class ReadStreamUtils:
     """
@@ -34,8 +42,24 @@ def url_to_stream(url):
         Downloads an image from a URL and returns it as a BytesIO.
         :param url: The URL of the image.
         :return: A BytesIO containing the image data.
+        :raises APIStatusError: the URL answered with an error status. Without
+            this the error page's bytes would be uploaded as the file.
+        :raises APIConnectionError: the download never got a response.
         """
-        response = httpx.get(url, follow_redirects=True)
+        try:
+            response = httpx.get(
+                url, follow_redirects=True, timeout=DOWNLOAD_TIMEOUT
+            )
+        except httpx.TimeoutException as exc:
+            raise APITimeoutError(f"Timed out downloading {url}") from exc
+        except httpx.TransportError as exc:
+            raise APIConnectionError(f"Failed to download {url}: {exc}") from exc
+        if response.is_error:
+            raise APIStatusError(
+                f"Failed to download {url}",
+                status_code=response.status_code,
+                response=response,
+            )
         return BytesIO(response.content)
 
     @staticmethod
diff --git a/tests/test_read_stream.py b/tests/test_read_stream.py
new file mode 100644
index 0000000..39cc064
--- /dev/null
+++ b/tests/test_read_stream.py
@@ -0,0 +1,73 @@
+"""URL inputs must fail loudly.
+
+A blob field given as a URL used to be fetched without checking the response,
+so a 404 page was uploaded to the API as if it were the file.
+"""
+
+import base64
+
+import httpx
+import pytest
+import respx
+
+from deepinfra import APIConnectionError, APIStatusError, APITimeoutError
+from deepinfra.utils.form_data import FormDataUtils
+from deepinfra.utils.read_stream import ReadStreamUtils
+
+URL = "https://example.com/audio.mp3"
+
+
+@respx.mock
+def test_url_download_returns_content():
+    respx.get(URL).mock(return_value=httpx.Response(200, content=b"audio-bytes"))
+
+    assert ReadStreamUtils.get_read_stream(URL).read() == b"audio-bytes"
+
+
+@respx.mock
+@pytest.mark.parametrize("status", [404, 401, 500])
+def test_error_status_raises_instead_of_uploading_the_error_page(status):
+    respx.get(URL).mock(return_value=httpx.Response(status, html="<h1>nope</h1>"))
+
+    with pytest.raises(APIStatusError) as exc_info:
+        ReadStreamUtils.get_read_stream(URL)
+
+    assert exc_info.value.status_code == status
+    assert URL in str(exc_info.value)
+
+
+@respx.mock
+def test_form_data_propagates_the_download_failure():
+    respx.get(URL).mock(return_value=httpx.Response(404))
+
+    with pytest.raises(APIStatusError):
+        FormDataUtils.get_form_data({"audio": URL}, blob_keys=["audio"])
+
+
+@respx.mock
+def test_connect_error_raises_api_connection_error():
+    respx.get(URL).mock(side_effect=httpx.ConnectError("no route"))
+
+    with pytest.raises(APIConnectionError):
+        ReadStreamUtils.get_read_stream(URL)
+
+
+@respx.mock
+def test_timeout_raises_api_timeout_error():
+    respx.get(URL).mock(side_effect=httpx.ReadTimeout("too slow"))
+
+    with pytest.raises(APITimeoutError):
+        ReadStreamUtils.get_read_stream(URL)
+
+
+def test_bytes_and_base64_inputs_are_unaffected():
+    assert ReadStreamUtils.get_read_stream(b"raw").read() == b"raw"
+
+    encoded = base64.b64encode(b"raw").decode()
+    data_uri = f"data:audio/mpeg;base64,{encoded}"
+    assert ReadStreamUtils.get_read_stream(data_uri).read() == b"raw"
+
+
+def test_missing_file_still_raises_file_not_found(tmp_path):
+    with pytest.raises(FileNotFoundError):
+        ReadStreamUtils.get_read_stream(str(tmp_path / "absent.wav"))