diff --git a/CHANGES.md b/CHANGES.md
new file mode 100644
index 0000000..07dd174
--- /dev/null
+++ b/CHANGES.md
@@ -0,0 +1,6 @@
+# changelog
+
+## Changes in 1.0.0
+
+- Breaking: The return value is now an **object** instead of a **string**
+- Added meta information, errors, and warnings
diff --git a/README.md b/README.md
index fcfe674..c471887 100644
--- a/README.md
+++ b/README.md
@@ -44,6 +44,15 @@ const pathStringC = roundedPolygonByCircumRadius({
 // set this to the "d" attribute of a <path> SVG element
 ```
 
+### return value
+
+The return value is an **object** with the following properties:
+
+- `d` (string) SVG path string to be used as a value to the `d` attributes of a `<path>` element
+- `meta` (object) contains helpful values: `sideLength`, `circumRadius`, `inRadius`, `minSideLength`, and `borderRadius`
+- `warnings` (an array of strings)
+- `errors` (an array of strings)
+
 ## `roundedPolygonBySideLength(options)`
 
 `options` properties
@@ -72,6 +81,15 @@ const pathStringS = roundedPolygonBySideLength({
 // set this to the "d" attribute of a <path> SVG element
 ```
 
+### return value
+
+The return value is an **object** with the following properties:
+
+- `d` (string) SVG path string to be used as a value to the `d` attributes of a `<path>` element
+- `meta` (object) contains helpful values: `sideLength`, `circumRadius`, `inRadius`, `minSideLength`, and `borderRadius`
+- `warnings` (an array of strings)
+- `errors` (an array of strings)
+
 ## Demos
 
 - [Codepen (UMD)](https://codepen.io/shreshthmohan/pen/mdpqaPY)