diff --git a/encoding/openapi/build.go b/encoding/openapi/build.go
index bc52f110f..01c07a03c 100644
--- a/encoding/openapi/build.go
+++ b/encoding/openapi/build.go
@@ -489,7 +489,7 @@ func (b *builder) disjunction(a []cue.Value, f typeFunc) {
 
 	for _, v := range a {
 		switch {
-		case v.Null() == nil:
+		case v.IsNull():
 			// TODO: for JSON schema, we need to fall through.
 			nullable = true
 
diff --git a/pkg/tool/exec/exec.go b/pkg/tool/exec/exec.go
index e8a0d743f..db6197e66 100644
--- a/pkg/tool/exec/exec.go
+++ b/pkg/tool/exec/exec.go
@@ -46,7 +46,7 @@ func (c *execCmd) Run(ctx *task.Context) (res interface{}, err error) {
 	// TODO: set environment variables, if defined.
 	stream := func(name string) (stream cue.Value, ok bool) {
 		c := ctx.Obj.LookupPath(cue.ParsePath(name))
-		if err := c.Null(); c.Err() != nil || err == nil {
+		if c.Err() != nil || c.IsNull() {
 			return
 		}
 		return c, true