diff --git a/prez/routers/curie.py b/prez/routers/curie.py
index 0b6a44be..d93df57e 100644
--- a/prez/routers/curie.py
+++ b/prez/routers/curie.py
@@ -1,6 +1,7 @@
-from fastapi import APIRouter
+from fastapi import APIRouter, HTTPException, status
 from fastapi.responses import PlainTextResponse
 from rdflib import URIRef
+from rdflib.term import _is_valid_uri
 
 from prez.services.curie_functions import get_uri_for_curie_id, get_curie_id_for_uri
 
@@ -11,15 +12,43 @@
     "/identifier/curie/{iri:path}",
     summary="Get the IRI's CURIE identifier",
     response_class=PlainTextResponse,
+    responses={
+        status.HTTP_400_BAD_REQUEST: {"content": {"application/json": {}}},
+        status.HTTP_500_INTERNAL_SERVER_ERROR: {"content": {"application/json": {}}},
+    },
 )
 def get_curie_route(iri: str):
-    return get_curie_id_for_uri(URIRef(iri))
+    if not _is_valid_uri(iri):
+        raise HTTPException(status.HTTP_400_BAD_REQUEST, f"Invalid characters in {iri}")
+    try:
+        return get_curie_id_for_uri(URIRef(iri))
+    except ValueError as err:
+        raise HTTPException(
+            status.HTTP_400_BAD_REQUEST, f"Error processing IRI {iri}"
+        ) from err
+    except Exception as err:
+        raise HTTPException(
+            status.HTTP_500_INTERNAL_SERVER_ERROR,
+            f"Unhandled server error for IRI {iri}",
+        ) from err
 
 
 @router.get(
     "/identifier/iri/{curie}",
     summary="Get the CURIE identifier's fully qualified IRI",
     response_class=PlainTextResponse,
+    responses={
+        status.HTTP_400_BAD_REQUEST: {"content": {"application/json": {}}},
+        status.HTTP_500_INTERNAL_SERVER_ERROR: {"content": {"application/json": {}}},
+    },
 )
 def get_iri_route(curie: str):
-    return get_uri_for_curie_id(curie)
+    try:
+        return get_uri_for_curie_id(curie)
+    except ValueError as err:
+        raise HTTPException(status.HTTP_400_BAD_REQUEST, str(err)) from err
+    except Exception as err:
+        raise HTTPException(
+            status.HTTP_500_INTERNAL_SERVER_ERROR,
+            f"Unhandled server error for curie {curie}",
+        ) from err
diff --git a/tests/curies/test_curie_endpoint.py b/tests/curies/test_curie_endpoint.py
new file mode 100644
index 00000000..2909374a
--- /dev/null
+++ b/tests/curies/test_curie_endpoint.py
@@ -0,0 +1,44 @@
+import pytest
+from fastapi.testclient import TestClient
+
+from prez.app import app
+
+
+@pytest.fixture
+def client() -> TestClient:
+    testclient = TestClient(app)
+
+    # Make a request for the following IRI to ensure
+    # the curie is available in the 'test_curie' test.
+    iri = "http://example.com/namespace/test"
+    response = testclient.get(f"/identifier/curie/{iri}")
+    assert response.status_code == 200
+    assert response.text == "nmspc:test"
+
+    return testclient
+
+
+@pytest.mark.parametrize(
+    "iri, expected_status_code",
+    [
+        ["d", 400],
+        ["http://!", 400],
+        ["http://example.com/namespace", 200],
+    ],
+)
+def test_iri(iri: str, expected_status_code: int, client: TestClient):
+    response = client.get(f"/identifier/curie/{iri}")
+    assert response.status_code == expected_status_code
+
+
+@pytest.mark.parametrize(
+    "curie, expected_status_code",
+    [
+        ["d", 400],
+        ["ns1", 400],
+        ["nmspc:test", 200],
+    ],
+)
+def test_curie(curie: str, expected_status_code: int, client: TestClient):
+    response = client.get(f"/identifier/iri/{curie}")
+    assert response.status_code == expected_status_code