diff --git a/api/app/routers/images.py b/api/app/routers/images.py
index ed5d2a5..b8fe795 100644
--- a/api/app/routers/images.py
+++ b/api/app/routers/images.py
@@ -30,7 +30,7 @@ def _error(detail: str, code: str, status: int):
 def _image_to_dict(
     image: Image, *, cdn_base: str | None = None, duplicate: bool | None = None
 ) -> dict[str, Any]:
-    _base = cdn_base.rstrip("/") if cdn_base else None
+    _base = cdn_base.strip().rstrip("/") if cdn_base else None
     file_url = f"{_base}/{image.storage_key}" if _base else f"/api/v1/images/{image.id}/file"
     thumbnail_url = (
         (f"{_base}/{image.thumbnail_key}" if _base else f"/api/v1/images/{image.id}/thumbnail")
diff --git a/api/tests/unit/test_url_construction.py b/api/tests/unit/test_url_construction.py
index 917e3f6..54bed6b 100644
--- a/api/tests/unit/test_url_construction.py
+++ b/api/tests/unit/test_url_construction.py
@@ -56,3 +56,10 @@ def test_cdn_trailing_slash_normalised():
     assert result["file_url"] == "https://cdn.example.com/abc123storagekey"
     assert result["thumbnail_url"] == "https://cdn.example.com/abc123storagekey-thumb"
     assert "//" not in result["file_url"].replace("https://", "")
+
+
+def test_cdn_trailing_whitespace_normalised():
+    img = _make_image(thumbnail_key="abc123storagekey-thumb")
+    result = _image_to_dict(img, cdn_base="https://cdn.example.com  ")
+    assert result["file_url"] == "https://cdn.example.com/abc123storagekey"
+    assert result["thumbnail_url"] == "https://cdn.example.com/abc123storagekey-thumb"