diff --git a/src/wp-includes/js/wp-emoji-loader.js b/src/wp-includes/js/wp-emoji-loader.js
index 9eec7be2f1..236415c162 100644
--- a/src/wp-includes/js/wp-emoji-loader.js
+++ b/src/wp-includes/js/wp-emoji-loader.js
@@ -66,6 +66,9 @@
 				 * To test for support, we try to render it, and compare the rendering to how it would look if
 				 * the browser doesn't render it correctly (white flag emoji + rainbow emoji).
 				 */
+				// Cleanup from previous test.
+				context.clearRect( 0, 0, canvas.width, canvas.height );
+
 				context.fillText( stringFromCharCode( 55356, 57331, 65039, 8205, 55356, 57096 ), 0, 0 );
 				flag = canvas.toDataURL();