diff --git a/packages/material-ui/src/FilledInput/FilledInput.js b/packages/material-ui/src/FilledInput/FilledInput.js
index a825d6890b68e0..11568a66103905 100644
--- a/packages/material-ui/src/FilledInput/FilledInput.js
+++ b/packages/material-ui/src/FilledInput/FilledInput.js
@@ -17,6 +17,7 @@ export const styles = theme => {
       backgroundColor: light ? 'rgba(0, 0, 0, 0.09)' : 'rgba(255, 255, 255, 0.09)',
       borderTopLeftRadius: theme.shape.borderRadius,
       borderTopRightRadius: theme.shape.borderRadius,
+      boxSizing: 'border-box',
       transition: theme.transitions.create('background-color', {
         duration: theme.transitions.duration.shorter,
         easing: theme.transitions.easing.easeOut,