diff --git a/internal/schemas/generator/go.go b/internal/schemas/generator/go.go
index c57784e8..f2f54ab8 100644
--- a/internal/schemas/generator/go.go
+++ b/internal/schemas/generator/go.go
@@ -214,6 +214,7 @@ import (
 	"time"
 
 	"github.com/oapi-codegen/runtime"
+	openapi_types "github.com/oapi-codegen/runtime/types"
 
 	{{- range .ExternalImports}}
 	{{ . }}
@@ -229,6 +230,7 @@ var (
 	_ json.RawMessage = nil
 	_ = fmt.Errorf
 	_ = runtime.JSONMerge
+	_ openapi_types.Email
 )
 `
 
diff --git a/internal/schemas/generator/runtimeobject.go b/internal/schemas/generator/runtimeobject.go
index 1acf5c6e..b993756a 100644
--- a/internal/schemas/generator/runtimeobject.go
+++ b/internal/schemas/generator/runtimeobject.go
@@ -35,6 +35,10 @@ const (
 	roRuntimeAlias  = "k8sruntime"
 	roRuntimeImport = "k8s.io/apimachinery/pkg/runtime"
 	roSchemaImport  = "k8s.io/apimachinery/pkg/runtime/schema"
+
+	// roOpenAPITypesAlias is the alias oapi-codegen uses for its formatted
+	// string types (Email, Date, File, UUID).
+	roOpenAPITypesAlias = "openapi_types"
 )
 
 // roScalarSelectorTypes are k8s types referenced via a package selector that are
@@ -216,7 +220,11 @@ func classifyElem(e ast.Expr, structs map[string]bool) fieldKind {
 		// pkg.Type — time.* and known alias types (Time, MicroTime, FieldsV1)
 		// are scalars; every other referenced package type is a generated struct
 		// with a DeepCopyInto method.
-		if pkg, ok := x.X.(*ast.Ident); ok && pkg.Name == "time" {
+		if pkg, ok := x.X.(*ast.Ident); ok && (pkg.Name == "time" || pkg.Name == roOpenAPITypesAlias) {
+			// oapi-codegen emits openapi_types.Email, Date, File and UUID for
+			// formatted strings. None of them has a DeepCopyInto method:
+			// Email is a string, UUID is an array, Date wraps a time.Time and
+			// File holds unexported fields. They copy by value.
 			return fkScalar
 		}
 		if roScalarSelectorTypes[x.Sel.Name] {
diff --git a/internal/schemas/generator/testdata/account_scaffold_definition.yaml b/internal/schemas/generator/testdata/account_scaffold_definition.yaml
index 95495fdf..977321fd 100644
--- a/internal/schemas/generator/testdata/account_scaffold_definition.yaml
+++ b/internal/schemas/generator/testdata/account_scaffold_definition.yaml
@@ -35,6 +35,13 @@ spec:
                       type: string
                       description: |
                         The name of the account to be scaffolded.
+                    members:
+                      type: array
+                      description: |
+                        Member principals for the account.
+                      items:
+                        type: string
+                        format: email
                   required:
                     - name
               required: