diff --git a/lib/css-tools.js b/lib/css-tools.js
index b2a1f5ff..a6a343c7 100644
--- a/lib/css-tools.js
+++ b/lib/css-tools.js
@@ -186,7 +186,7 @@ function csstreeToStyleDeclaration(declaration) {
  * Gets the CSS string of a style element
  *
  * @param {Object} elem style element
- * @return {string|Array} CSS string or empty array if no styles are set
+ * @return {string} CSS string or empty array if no styles are set
  */
 function getCssStr(elem) {
   if (elem.content[0].type === 'text' || elem.content[0].type === 'cdata') {
@@ -200,7 +200,7 @@ function getCssStr(elem) {
  *
  * @param {Object} elem style element
  * @param {string} css string to be set
- * @return {Object} reference to field with CSS
+ * @return {string} reference to field with CSS
  */
 function setCssStr(elem, css) {
   if (elem.content[0].type === 'text' || elem.content[0].type === 'cdata') {