diff --git a/src/net/http/request.go b/src/net/http/request.go
index 7a86322f94..2d65ca3c8a 100644
--- a/src/net/http/request.go
+++ b/src/net/http/request.go
@@ -785,7 +785,9 @@ func NewRequest(method, urlStr string, body io.Reader) (*Request, error) {
 				return ioutil.NopCloser(&r), nil
 			}
 		default:
-			req.ContentLength = -1 // unknown
+			if body != NoBody {
+				req.ContentLength = -1 // unknown
+			}
 		}
 		// For client requests, Request.ContentLength of 0
 		// means either actually 0, or unknown. The only way
diff --git a/src/net/http/request_test.go b/src/net/http/request_test.go
index 3c965c1e8a..483c025fb0 100644
--- a/src/net/http/request_test.go
+++ b/src/net/http/request_test.go
@@ -825,6 +825,16 @@ func TestNewRequestGetBody(t *testing.T) {
 	}
 }
 
+func TestNewRequestNoBody(t *testing.T) {
+	req, err := NewRequest("GET", "http://foo.com/", NoBody)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if req.ContentLength != 0 {
+		t.Errorf("ContentLength = %d; want 0", req.ContentLength)
+	}
+}
+
 func testMissingFile(t *testing.T, req *Request) {
 	f, fh, err := req.FormFile("missing")
 	if f != nil {