diff --git a/internal/token.go b/internal/token.go
index e83ddeef0..3359ca362 100644
--- a/internal/token.go
+++ b/internal/token.go
@@ -50,6 +50,11 @@ type Token struct {
 	// mechanisms for that TokenSource will not be used.
 	Expiry time.Time
 
+	// ExpiresIn is the OAuth2 wire format "expires_in" field,
+	// which specifies how many seconds later the token expires,
+	// relative to an unknown time base approximately around "now".
+	ExpiresIn int64
+
 	// Raw optionally contains extra metadata from the server
 	// when updating a token.
 	Raw interface{}
@@ -295,6 +300,7 @@ func doTokenRoundTrip(ctx context.Context, req *http.Request) (*Token, error) {
 		expires, _ := strconv.Atoi(e)
 		if expires != 0 {
 			token.Expiry = time.Now().Add(time.Duration(expires) * time.Second)
+			token.ExpiresIn = int64(expires)
 		}
 	default:
 		var tj tokenJSON
@@ -312,6 +318,7 @@ func doTokenRoundTrip(ctx context.Context, req *http.Request) (*Token, error) {
 			TokenType:    tj.TokenType,
 			RefreshToken: tj.RefreshToken,
 			Expiry:       tj.expiry(),
+			ExpiresIn:    int64(tj.ExpiresIn),
 			Raw:          make(map[string]interface{}),
 		}
 		json.Unmarshal(body, &token.Raw) // no error checks for optional fields
diff --git a/token.go b/token.go
index 109997d77..ad191b4f3 100644
--- a/token.go
+++ b/token.go
@@ -163,6 +163,7 @@ func tokenFromInternal(t *internal.Token) *Token {
 		TokenType:    t.TokenType,
 		RefreshToken: t.RefreshToken,
 		Expiry:       t.Expiry,
+		ExpiresIn:    t.ExpiresIn,
 		raw:          t.Raw,
 	}
 }