diff --git a/src/pkg/net/udp_test.go b/src/pkg/net/udp_test.go
--- a/src/pkg/net/udp_test.go
+++ b/src/pkg/net/udp_test.go
@@ -9,6 +9,7 @@
 	"runtime"
 	"strings"
 	"testing"
+	"time"
 )
 
 func TestResolveUDPAddr(t *testing.T) {
@@ -251,3 +252,35 @@
 		}
 	}
 }
+
+func TestUDPReadFrom(t *testing.T) {
+	const raddr = "54.244.132.193:55555"
+	c, err := Dial("udp", raddr)
+	if err != nil {
+		t.Fatalf("Dial failed: %v", err)
+	}
+	defer c.Close()
+
+	ra, err := ResolveUDPAddr("udp", raddr)
+	if err != nil {
+		t.Fatalf("ResolveUDPAddr failed: %v", err)
+	}
+
+	_, err = c.(*UDPConn).WriteToUDP([]byte("a"), ra)
+	if err == nil {
+		t.Fatal("WriteToUDP should fail")
+	}
+	if err != nil && err.(*OpError).Err != ErrWriteToConnected {
+		t.Fatalf("WriteToUDP should fail as ErrWriteToConnected: %v", err)
+	}
+
+	err = c.SetDeadline(time.Now().Add(100 * time.Millisecond))
+	if err != nil {
+		t.Fatalf("SetDeadline failed: %v", err)
+	}
+	b := make([]byte, 1)
+	_, _, err = c.(*UDPConn).ReadFromUDP(b)
+	if err != nil && !isTimeout(err) {
+		t.Fatalf("ReadFromUDP failed: %v", err)
+	}
+}