diff --git a/services/acl/Acl.IntegrationTests/OpenZaakFixture.cs b/services/acl/Acl.IntegrationTests/OpenZaakFixture.cs
index a743913..32dece6 100644
--- a/services/acl/Acl.IntegrationTests/OpenZaakFixture.cs
+++ b/services/acl/Acl.IntegrationTests/OpenZaakFixture.cs
@@ -77,6 +77,18 @@ public sealed class OpenZaakFixture : IDisposable
         return JsonDocument.Parse(json).RootElement.Clone();
     }
 
+    /// <summary>The URL of the published "Diploma" informatieobjecttype (S-10b), or null when the
+    /// stack has not been seeded with OZ_PUBLISH=1. `status=definitief` returns published types only.</summary>
+    public async Task<Uri?> FindPublishedDiplomaInformatieobjecttypeAsync(CancellationToken ct = default)
+    {
+        var query = new Uri(BaseUrl, "/catalogi/api/v1/informatieobjecttypen?status=definitief");
+        var page = await GetJsonAsync(query, ct);
+        foreach (var iot in page.GetProperty("results").EnumerateArray())
+            if (iot.TryGetProperty("omschrijving", out var o) && o.GetString() == "Diploma")
+                return new Uri(iot.GetProperty("url").GetString()!);
+        return null;
+    }
+
     /// <summary>The zaaktype's eindstatus (terminal statustype) URL — the one an approval sets.</summary>
     public async Task<Uri> FindEindstatustypeAsync(Uri zaaktypeUrl, CancellationToken ct = default)
     {
diff --git a/services/acl/Acl.IntegrationTests/OpenZaakGatewayIntegrationTests.cs b/services/acl/Acl.IntegrationTests/OpenZaakGatewayIntegrationTests.cs
index 9cdac3c..1a7a87a 100644
--- a/services/acl/Acl.IntegrationTests/OpenZaakGatewayIntegrationTests.cs
+++ b/services/acl/Acl.IntegrationTests/OpenZaakGatewayIntegrationTests.cs
@@ -74,4 +74,55 @@ public sealed class OpenZaakGatewayIntegrationTests(OpenZaakFixture stack)
         var eindstatustype = await stack.FindEindstatustypeAsync(zaaktype!);
         Assert.Equal(eindstatustype.ToString(), status.GetProperty("statustype").GetString());
     }
+
+    [Fact]
+    public async Task Storing_a_diploma_creates_a_real_informatieobject_related_to_the_zaak()
+    {
+        var zaaktype = await stack.FindPublishedBigZaaktypeAsync();
+        Assert.True(zaaktype is not null,
+            "No published BIG-REGISTRATIE zaaktype found — seed the stack with OZ_PUBLISH=1.");
+        var informatieobjecttype = await stack.FindPublishedDiplomaInformatieobjecttypeAsync();
+        Assert.True(informatieobjecttype is not null,
+            "No published Diploma informatieobjecttype found — seed the stack with OZ_PUBLISH=1.");
+
+        var gateway = new OpenZaakGateway(stack.Http, stack.Options);
+        var zaakUrl = await gateway.OpenZaakAsync(new ZaakRequest(
+            Bronorganisatie: "517439943",
+            VerantwoordelijkeOrganisatie: "517439943",
+            Vertrouwelijkheidaanduiding: "openbaar",
+            Zaaktype: zaaktype!,
+            Startdatum: DateOnly.FromDateTime(DateTime.UtcNow),
+            Identificatie: Guid.NewGuid().ToString()));
+
+        var content = System.Text.Encoding.UTF8.GetBytes("%PDF-1.4 synthetic diploma\n");
+        var documentUrl = await gateway.StoreDocumentAsync(new DocumentRequest(
+            Bronorganisatie: "517439943",
+            Informatieobjecttype: informatieobjecttype!,
+            Vertrouwelijkheidaanduiding: "openbaar",
+            Zaak: zaakUrl,
+            Creatiedatum: DateOnly.FromDateTime(DateTime.UtcNow),
+            Titel: "Diploma",
+            Auteur: "zorgprofessional",
+            Taal: "nld",
+            Bestandsnaam: "diploma.pdf",
+            Formaat: "application/pdf",
+            Inhoud: content));
+
+        // The gateway returns the canonical informatieobject URL...
+        Assert.StartsWith(
+            new Uri(stack.BaseUrl, "/documenten/api/v1/enkelvoudiginformatieobjecten/").ToString(),
+            documentUrl.ToString());
+
+        // ...the document is really persisted with the default-filled fields...
+        var doc = await stack.GetJsonAsync(documentUrl);
+        Assert.Equal("diploma.pdf", doc.GetProperty("bestandsnaam").GetString());
+        Assert.Equal(informatieobjecttype.ToString(), doc.GetProperty("informatieobjecttype").GetString());
+        Assert.Equal(content.Length, doc.GetProperty("bestandsomvang").GetInt32());
+
+        // ...and it is related to the zaak (a zaakinformatieobject links the two).
+        var relations = await stack.GetJsonAsync(new Uri(stack.BaseUrl,
+            "/zaken/api/v1/zaakinformatieobjecten?informatieobject=" + Uri.EscapeDataString(documentUrl.ToString())));
+        Assert.Contains(relations.EnumerateArray(),
+            r => r.GetProperty("zaak").GetString() == zaakUrl.ToString());
+    }
 }
diff --git a/tests/e2e/registration.spec.ts b/tests/e2e/registration.spec.ts
index b508352..8274ecb 100644
--- a/tests/e2e/registration.spec.ts
+++ b/tests/e2e/registration.spec.ts
@@ -56,6 +56,11 @@ test('DigiD submit → public INGEDIEND → documenten → behandelaar goedkeurt
   // why we supply the documents here rather than right after submit, when the trigger would race the
   // wait and no-op. (S-10b turns this into a real file upload; here it is the trigger that unblocks
   // beoordeling.)
+  await page.setInputFiles('#diploma', {
+    name: 'diploma.pdf',
+    mimeType: 'application/pdf',
+    buffer: Buffer.from('%PDF-1.4 synthetic diploma\n'),
+  });
   await page.getByRole('button', { name: /documenten aanleveren/i }).click();
   await expect(page.getByText(/documenten zijn aangeleverd/i)).toBeVisible();