diff --git a/client/llb/exec.go b/client/llb/exec.go
index 457a9b1f2f8e..faba8bddc72b 100644
--- a/client/llb/exec.go
+++ b/client/llb/exec.go
@@ -396,6 +396,7 @@ func (e *ExecOp) Marshal(ctx context.Context, c *Constraints) (digest.Digest, []
 			})
 		} else {
 			pm := &pb.Mount{
+				Input:     pb.Empty,
 				Dest:      s.Target,
 				MountType: pb.MountType_SECRET,
 				SecretOpt: &pb.SecretOpt{
@@ -412,6 +413,7 @@ func (e *ExecOp) Marshal(ctx context.Context, c *Constraints) (digest.Digest, []
 
 	for _, s := range e.ssh {
 		pm := &pb.Mount{
+			Input:     pb.Empty,
 			Dest:      s.Target,
 			MountType: pb.MountType_SSH,
 			SSHOpt: &pb.SSHOpt{