diff --git a/internal/crd/generator.go b/internal/crd/generator.go
index fd79145..bed7540 100644
--- a/internal/crd/generator.go
+++ b/internal/crd/generator.go
@@ -20,7 +20,9 @@ import (
 	"path/filepath"
 
 	"github.com/spf13/afero"
+	"k8s.io/apiextensions-apiserver/pkg/apis/apiextensions"
 	apiextensionsv1 "k8s.io/apiextensions-apiserver/pkg/apis/apiextensions/v1"
+	structuralschema "k8s.io/apiextensions-apiserver/pkg/apiserver/schema"
 	"sigs.k8s.io/yaml"
 
 	"github.com/crossplane/crossplane-runtime/v2/pkg/errors"
@@ -44,6 +46,10 @@ func createCRDFromXRD(xrd xpv1.CompositeResourceDefinition) (*apiextensionsv1.Cu
 		xrCrd.Spec.Names.ListKind = xrCrd.Spec.Names.Kind + "List"
 	}
 
+	if err := validateStructural(xrCrd); err != nil {
+		return nil, nil, errors.Wrapf(err, "composite CRD derived from XRD %q has an unusable schema", xrd.GetName())
+	}
+
 	if xrd.Spec.ClaimNames != nil {
 		claimCrd, err = xcrd.ForCompositeResourceClaim(&xrd)
 		if err != nil {
@@ -59,6 +65,35 @@ func createCRDFromXRD(xrd xpv1.CompositeResourceDefinition) (*apiextensionsv1.Cu
 	return xrCrd, claimCrd, nil
 }
 
+// validateStructural reports schemas that Kubernetes would not accept as
+// structural. Such a schema is silently reduced to an empty object when it is
+// converted to OpenAPI, which leaves the generated language types with no
+// fields at all rather than with the one bad field missing, so it is worth
+// stopping on rather than passing through.
+func validateStructural(crd *apiextensionsv1.CustomResourceDefinition) error {
+	for _, ver := range crd.Spec.Versions {
+		if ver.Schema == nil || ver.Schema.OpenAPIV3Schema == nil {
+			continue
+		}
+
+		internal := &apiextensions.JSONSchemaProps{}
+		if err := apiextensionsv1.Convert_v1_JSONSchemaProps_To_apiextensions_JSONSchemaProps(ver.Schema.OpenAPIV3Schema, internal, nil); err != nil {
+			return errors.Wrapf(err, "cannot read the schema of version %q", ver.Name)
+		}
+
+		s, err := structuralschema.NewStructural(internal)
+		if err != nil {
+			return errors.Wrapf(err, "version %q", ver.Name)
+		}
+
+		if err := structuralschema.ValidateStructural(nil, s).ToAggregate(); err != nil {
+			return errors.Wrapf(err, "version %q", ver.Name)
+		}
+	}
+
+	return nil
+}
+
 // ProcessXRD generates associated CRDs from an XRD.
 func ProcessXRD(fs afero.Fs, bs []byte, path, baseFolder string) (string, string, error) {
 	var xrd xpv1.CompositeResourceDefinition
diff --git a/internal/crd/generator_test.go b/internal/crd/generator_test.go
index 7e1f3aa..5e294ce 100644
--- a/internal/crd/generator_test.go
+++ b/internal/crd/generator_test.go
@@ -17,6 +17,7 @@ limitations under the License.
 package crd
 
 import (
+	"strings"
 	"testing"
 
 	"github.com/google/go-cmp/cmp"
@@ -33,6 +34,9 @@ var claimableXRDBytes []byte
 //go:embed testdata/unclaimable-xrd.yaml
 var unclaimableXRDBytes []byte
 
+//go:embed testdata/untyped-field-xrd.yaml
+var untypedFieldXRDBytes []byte
+
 func TestProcessXRD(t *testing.T) {
 	t.Parallel()
 
@@ -44,6 +48,8 @@ func TestProcessXRD(t *testing.T) {
 
 		expectedClaimKind     string
 		expectedClaimListKind string
+
+		expectedErr string
 	}{
 		"ClaimableXRD": {
 			xrdBytes:              claimableXRDBytes,
@@ -57,6 +63,10 @@ func TestProcessXRD(t *testing.T) {
 			expectedXRKind:     "XInternalBucket",
 			expectedXRListKind: "XInternalBucketList",
 		},
+		"XRDWithAnUntypedField": {
+			xrdBytes:    untypedFieldXRDBytes,
+			expectedErr: `properties[spec].properties[parameters].properties[acl].type: Required value: must not be empty for specified object fields`,
+		},
 	}
 
 	for name, tc := range tcs {
@@ -65,6 +75,15 @@ func TestProcessXRD(t *testing.T) {
 
 			outFS := afero.NewMemMapFs()
 			xrPath, claimPath, err := ProcessXRD(outFS, tc.xrdBytes, "output", "/")
+			if tc.expectedErr != "" {
+				if err == nil {
+					t.Fatalf("expected an error mentioning %q, got none", tc.expectedErr)
+				}
+				if !strings.Contains(err.Error(), tc.expectedErr) {
+					t.Fatalf("expected the error to mention %q, got: %v", tc.expectedErr, err)
+				}
+				return
+			}
 			if err != nil {
 				t.Fatal(err)
 			}
diff --git a/internal/crd/testdata/untyped-field-xrd.yaml b/internal/crd/testdata/untyped-field-xrd.yaml
new file mode 100644
index 0000000..81d7592
--- /dev/null
+++ b/internal/crd/testdata/untyped-field-xrd.yaml
@@ -0,0 +1,32 @@
+apiVersion: apiextensions.crossplane.io/v1
+kind: CompositeResourceDefinition
+metadata:
+  name: xuntypedbuckets.platform.example.com
+spec:
+  group: platform.example.com
+  names:
+    categories:
+    - crossplane
+    kind: XUntypedBucket
+    plural: xuntypedbuckets
+  versions:
+  - name: v1alpha1
+    referenceable: true
+    schema:
+      openAPIV3Schema:
+        description: UntypedBucket is the Schema for the UntypedBucket API.
+        properties:
+          spec:
+            description: UntypedBucketSpec defines the desired state of UntypedBucket.
+            properties:
+              parameters:
+                properties:
+                  acl:
+                    description: This property has no type, which is not structural.
+                type: object
+            type: object
+          status:
+            description: UntypedBucketStatus defines the observed state of UntypedBucket.
+            type: object
+        type: object
+    served: true