diff --git a/optimade/server/config.py b/optimade/server/config.py
index dd45a3bad..1ba800f13 100644
--- a/optimade/server/config.py
+++ b/optimade/server/config.py
@@ -240,7 +240,7 @@ class ServerConfig(BaseSettings):
     ] = "localhost:27017"
 
     license: Annotated[
-        str | AnyHttpUrl | None,
+        AnyHttpUrl | str | None,
         Field(
             description="""Either an SPDX license identifier or a URL to a human-readable license, used to populate the `license` field in the info response.
 
@@ -480,7 +480,9 @@ def check_license_info(cls, value: Any) -> AnyHttpUrl | None:
         if not value:
             return None
 
-        if not isinstance(value, AnyHttpUrl):
+        try:
+            value = AnyHttpUrl(value)
+        except ValueError:
             value = f"https://spdx.org/licenses/{value}"
 
         # Check if license URL is accessible