diff --git a/packages/pigment-css-react/src/Grid.jsx b/packages/pigment-css-react/src/Grid.jsx
index edf10101..53f76cac 100644
--- a/packages/pigment-css-react/src/Grid.jsx
+++ b/packages/pigment-css-react/src/Grid.jsx
@@ -300,6 +300,7 @@ process.env.NODE_ENV !== 'production' &&
      */
     size: PropTypes /* @typescript-to-proptypes-ignore */.oneOfType([
       PropTypes.arrayOf(PropTypes.number),
+      PropTypes.oneOf(['grow', 'auto']),
       PropTypes.number,
       PropTypes.object,
     ]),
diff --git a/packages/pigment-css-react/tests/Grid/fixtures/Grid.output.js b/packages/pigment-css-react/tests/Grid/fixtures/Grid.output.js
index 1ef8c27b..206e8ab2 100644
--- a/packages/pigment-css-react/tests/Grid/fixtures/Grid.output.js
+++ b/packages/pigment-css-react/tests/Grid/fixtures/Grid.output.js
@@ -394,6 +394,7 @@ process.env.NODE_ENV !== 'production' &&
      */
     size: PropTypes /* @typescript-to-proptypes-ignore */.oneOfType([
       PropTypes.arrayOf(PropTypes.number),
+      PropTypes.oneOf(['grow', 'auto']),
       PropTypes.number,
       PropTypes.object,
     ]),