diff --git a/cmd/cue/cmd/common.go b/cmd/cue/cmd/common.go
index abbd479af..b099b3ae9 100644
--- a/cmd/cue/cmd/common.go
+++ b/cmd/cue/cmd/common.go
@@ -607,6 +607,11 @@ func parseArgs(cmd *Command, args []string, cfg *config) (p *buildPlan, err erro
 				"-d/--schema flag specified without a schema")
 		}
 
+		if p.schema != nil && len(values) == 0 {
+			return nil, errors.Newf(token.NoPos,
+				"-d/--schema flag requires non-CUE input files")
+		}
+
 		switch {
 		default:
 			fallthrough
diff --git a/cmd/cue/cmd/testdata/script/def_issue4350.txtar b/cmd/cue/cmd/testdata/script/def_issue4350.txtar
index de42a6b7a..5060a084c 100644
--- a/cmd/cue/cmd/testdata/script/def_issue4350.txtar
+++ b/cmd/cue/cmd/testdata/script/def_issue4350.txtar
@@ -6,8 +6,8 @@ cmp stdout def.stdout
 exec cue def -e '#Schema' in.cue
 cmp stdout def-e.stdout
 
-exec cue def -d '#Schema' in.cue
-cmp stdout def-d.stdout
+! exec cue def -d '#Schema' in.cue
+cmp stderr def-d.stderr
 
 -- in.cue --
 #Schema: {
@@ -26,8 +26,5 @@ _#def: {
 	a?: string
 	b?: b2?: string
 }
--- def-d.stdout --
-#Schema: {
-	a?: string
-	b?: b2?: string
-}
+-- def-d.stderr --
+-d/--schema flag requires non-CUE input files