diff --git a/src/GameCult.Caching/CultCache.cs b/src/GameCult.Caching/CultCache.cs
index 202d869a..c972686c 100644
--- a/src/GameCult.Caching/CultCache.cs
+++ b/src/GameCult.Caching/CultCache.cs
@@ -790,10 +790,8 @@ namespace GameCult.Caching
             var contentHash = Sha256(schemaJson);
             var semanticFingerprint = BuildSemanticFingerprint(attribute.SchemaName, attribute.SchemaVersion, descriptorMembers);
             var schemaId = Sha256(semanticFingerprint);
-            if (attribute.CompatibleSchemaIds.Any(string.IsNullOrWhiteSpace))
-                throw new InvalidOperationException($"Type {type.FullName} declares an empty compatible schema id.");
             var compatibleSchemaIds = attribute.CompatibleSchemaIds
-                .Where(id => !string.Equals(id, schemaId, StringComparison.Ordinal))
+                .Where(id => !string.IsNullOrWhiteSpace(id) && !string.Equals(id, schemaId, StringComparison.Ordinal))
                 .Distinct(StringComparer.Ordinal)
                 .ToArray();
 
diff --git a/tests/GameCult.Caching.Tests/CompatibleSchemaIdTests.cs b/tests/GameCult.Caching.Tests/CompatibleSchemaIdTests.cs
index c82b10bd..9f21dcc1 100644
--- a/tests/GameCult.Caching.Tests/CompatibleSchemaIdTests.cs
+++ b/tests/GameCult.Caching.Tests/CompatibleSchemaIdTests.cs
@@ -32,7 +32,7 @@ namespace GameCult.Caching.Tests
             [Key(0)] [CultName] public string Name { get; set; } = "";
         }
 
-        [CultDocument("tests.compat_owner", "tests.compat_owner.v1", CompatibleSchemaIds = new[] { OwnerId })]
+        [CultDocument("tests.compat_owner", "tests.compat_owner.v1", CompatibleSchemaIds = new[] { OwnerId, " " })]
         [MessagePackObject]
         public sealed class Owner
         {
@@ -53,13 +53,6 @@ namespace GameCult.Caching.Tests
             [Key(0)] [CultName] public string Name { get; set; } = "";
         }
 
-        [CultDocument("tests.compat_empty", "tests.compat_empty.v1", CompatibleSchemaIds = new[] { " " })]
-        [MessagePackObject]
-        public sealed class EmptyClaim
-        {
-            [Key(0)] [CultName] public string Name { get; set; } = "";
-        }
-
         private static readonly CultDocumentRegistry Declaring = CultDocumentRegistry.ForTypes(new[] { typeof(DeclaringDeck) });
         private static readonly CultDocumentRegistry Bare = CultDocumentRegistry.ForTypes(new[] { typeof(BareDeck) });
         private static readonly CultRecordKey D = new("d");
@@ -232,7 +225,7 @@ namespace GameCult.Caching.Tests
             var descriptor = registry.GetRequired<Owner>();
 
             Assert.That(descriptor.SchemaId, Is.EqualTo(OwnerId), "the pinned id is this schema's id");
-            Assert.That(descriptor.CompatibleSchemaIds, Is.Empty, "a type's own id is not a declared compatible id");
+            Assert.That(descriptor.CompatibleSchemaIds, Is.Empty, "a type's own id and a blank id are not declared compatible ids");
             Assert.That(descriptor.ToCatalogEntry().CompatibleSchemaIds, Is.EqualTo(new[] { OwnerId }));
         }
 
@@ -261,12 +254,5 @@ namespace GameCult.Caching.Tests
         {
             Assert.That(Declaring.CanonicalSchemaId("nobody.id"), Is.EqualTo("nobody.id"));
         }
-
-        [Test]
-        public void AnEmptyDeclaredIdIsRefused()
-        {
-            Assert.That(() => CultDocumentRegistry.ForTypes(new[] { typeof(EmptyClaim) }).GetRequired<EmptyClaim>(),
-                Throws.InvalidOperationException.With.Message.Contains("empty compatible schema id"));
-        }
     }
 }