diff --git a/go/pserver/client.go b/go/pserver/client.go
index dda915977282d4880ddcc8c18ef6fd80ede9e01b..6938b9d5ce6f6d73c05bd6e3154777023965c319 100644
--- a/go/pserver/client.go
+++ b/go/pserver/client.go
@@ -1,6 +1,7 @@
 package pserver
 
 import (
+	"errors"
 	"hash/fnv"
 	"sort"
 	"time"
@@ -123,6 +124,9 @@ func (c *Client) FinishInitParams() error {
 // SendGrads sends gradients to parameter servers for updating
 // parameters.
 func (c *Client) SendGrads(grads []Gradient) error {
+	if len(grads) == 0 {
+		return errors.New("no gradient received")
+	}
 	errCh := make(chan error, len(grads))
 	for _, g := range grads {
 		go func(g Gradient) {