diff --git a/models/token.go b/models/token.go
index 1245098df..49541b122 100644
--- a/models/token.go
+++ b/models/token.go
@@ -57,9 +57,15 @@ func GetAccessTokenBySHA(token string) (*AccessToken, error) {
 	if token == "" {
 		return nil, ErrAccessTokenEmpty{}
 	}
-	if len(token) < 8 {
+	// A token is defined as being SHA1 sum these are 40 hexadecimal bytes long
+	if len(token) != 40 {
 		return nil, ErrAccessTokenNotExist{token}
 	}
+	for _, x := range []byte(token) {
+		if x < '0' || (x > '9' && x < 'a') || x > 'f' {
+			return nil, ErrAccessTokenNotExist{token}
+		}
+	}
 	var tokens []AccessToken
 	lastEight := token[len(token)-8:]
 	err := x.Table(&AccessToken{}).Where("token_last_eight = ?", lastEight).Find(&tokens)