diff --git a/builder/hyperv/iso/builder.go b/builder/hyperv/iso/builder.go
index e6c8d4d67..657c07886 100644
--- a/builder/hyperv/iso/builder.go
+++ b/builder/hyperv/iso/builder.go
@@ -92,7 +92,8 @@ type Config struct {
 // Prepare processes the build configuration parameters.
 func (b *Builder) Prepare(raws ...interface{}) ([]string, error) {
 	err := config.Decode(&b.config, &config.DecodeOpts{
-		Interpolate: true,
+		Interpolate:        true,
+		InterpolateContext: &b.config.ctx,
 		InterpolateFilter: &interpolate.RenderFilter{
 			Exclude: []string{
 				"boot_command",