diff --git a/cmd/nvidia-ctk/cdi/generate/generate.go b/cmd/nvidia-ctk/cdi/generate/generate.go
index c9a146fb..4e930e05 100644
--- a/cmd/nvidia-ctk/cdi/generate/generate.go
+++ b/cmd/nvidia-ctk/cdi/generate/generate.go
@@ -35,9 +35,6 @@ import (
 )
 
 const (
-	formatJSON = "json"
-	formatYAML = "yaml"
-
 	allDeviceName = "all"
 )
 
@@ -87,7 +84,7 @@ func (m command) build() *cli.Command {
 		&cli.StringFlag{
 			Name:        "format",
 			Usage:       "The output format for the generated spec [json | yaml]. This overrides the format defined by the output file extension (if specified).",
-			Value:       formatYAML,
+			Value:       spec.FormatYAML,
 			Destination: &cfg.format,
 		},
 		&cli.StringFlag{
@@ -121,8 +118,8 @@ func (m command) validateFlags(c *cli.Context, cfg *config) error {
 
 	cfg.format = strings.ToLower(cfg.format)
 	switch cfg.format {
-	case formatJSON:
-	case formatYAML:
+	case spec.FormatJSON:
+	case spec.FormatYAML:
 	default:
 		return fmt.Errorf("invalid output format: %v", cfg.format)
 	}
@@ -160,7 +157,7 @@ func (m command) run(c *cli.Context, cfg *config) error {
 	if err != nil {
 		return fmt.Errorf("failed to generate CDI spec: %v", err)
 	}
-	m.logger.Infof("Generated CDI spec with version", spec.Raw().Version)
+	m.logger.Infof("Generated CDI spec with version %v", spec.Raw().Version)
 
 	if cfg.output == "" {
 		_, err := spec.WriteTo(os.Stdout)
@@ -181,11 +178,9 @@ func formatFromFilename(filename string) string {
 	ext := filepath.Ext(filename)
 	switch strings.ToLower(ext) {
 	case ".json":
-		return formatJSON
-	case ".yaml":
-		return formatYAML
-	case ".yml":
-		return formatYAML
+		return spec.FormatJSON
+	case ".yaml", ".yml":
+		return spec.FormatYAML
 	}
 
 	return ""
diff --git a/pkg/nvcdi/spec/api.go b/pkg/nvcdi/spec/api.go
index e79216c2..a72c6dff 100644
--- a/pkg/nvcdi/spec/api.go
+++ b/pkg/nvcdi/spec/api.go
@@ -25,6 +25,11 @@ import (
 const (
 	// DetectMinimumVersion is a constant that triggers a spec to detect the minimum required version.
 	DetectMinimumVersion = "DETECT_MINIMUM_VERSION"
+
+	// FormatJSON indicates a JSON output format
+	FormatJSON = "json"
+	// FormatYAML indicates a YAML output format
+	FormatYAML = "yaml"
 )
 
 // Interface is the interface for the spec API
diff --git a/pkg/nvcdi/spec/builder.go b/pkg/nvcdi/spec/builder.go
index e8fc4b71..bdf68fe2 100644
--- a/pkg/nvcdi/spec/builder.go
+++ b/pkg/nvcdi/spec/builder.go
@@ -33,8 +33,8 @@ type builder struct {
 	format      string
 }
 
-// NewBuilder creates a new spec builder with the supplied options
-func NewBuilder(opts ...Option) *builder {
+// newBuilder creates a new spec builder with the supplied options
+func newBuilder(opts ...Option) *builder {
 	s := &builder{}
 	for _, opt := range opts {
 		opt(s)
@@ -48,6 +48,9 @@ func NewBuilder(opts ...Option) *builder {
 	if s.class == "" {
 		s.class = "gpu"
 	}
+	if s.format == "" {
+		s.format = FormatYAML
+	}
 
 	return s
 }
diff --git a/pkg/nvcdi/spec/spec.go b/pkg/nvcdi/spec/spec.go
index 961993a2..c0e96946 100644
--- a/pkg/nvcdi/spec/spec.go
+++ b/pkg/nvcdi/spec/spec.go
@@ -34,7 +34,7 @@ var _ Interface = (*spec)(nil)
 
 // New creates a new spec with the specified options.
 func New(opts ...Option) (Interface, error) {
-	return NewBuilder(opts...).Build()
+	return newBuilder(opts...).Build()
 }
 
 // Save writes the spec to the specified path and overwrites the file if it exists.
@@ -98,9 +98,9 @@ func (s *spec) normalizePath(path string) string {
 
 func (s *spec) extension() string {
 	switch s.format {
-	case "json":
+	case FormatJSON:
 		return ".json"
-	case "yaml", "yml":
+	case FormatYAML:
 		return ".yaml"
 	}