diff --git a/client/llb/definition.go b/client/llb/definition.go
index 14486dc088535..cdd320897cc5f 100644
--- a/client/llb/definition.go
+++ b/client/llb/definition.go
@@ -29,9 +29,11 @@ type DefinitionOp struct {
 	inputCache *sync.Map // shared and written among DefinitionOps so avoid race on this map using sync.Map
 }
 
+var empty = &pb.Definition{}
+
 // NewDefinitionOp returns a new operation from a marshalled definition.
 func NewDefinitionOp(def *pb.Definition) (*DefinitionOp, error) {
-	if def == nil {
+	if def == nil || proto.Equal(def, empty) {
 		return nil, errors.New("invalid nil input definition to definition op")
 	}