diff --git a/projects/plugins/jetpack/changelog/fix-atomic-php-warnings b/projects/plugins/jetpack/changelog/fix-atomic-php-warnings
new file mode 100644
index 0000000000000..f7140c8de270b
--- /dev/null
+++ b/projects/plugins/jetpack/changelog/fix-atomic-php-warnings
@@ -0,0 +1,4 @@
+Significance: patch
+Type: other
+
+Compat: wp_startswith should only pass to strpos if string is passed.
diff --git a/projects/plugins/jetpack/functions.compat.php b/projects/plugins/jetpack/functions.compat.php
index 40715d2598e66..ebaf7903e0fef 100644
--- a/projects/plugins/jetpack/functions.compat.php
+++ b/projects/plugins/jetpack/functions.compat.php
@@ -86,11 +86,14 @@ function youtube_sanitize_url( $url ) {
 	/**
 	 * Check whether a string starts with a specific substring.
 	 *
-	 * @param var    $haystack String we are filtering.
+	 * @param string $haystack String we are filtering.
 	 * @param string $needle The substring we are looking for.
 	 * @return bool
 	 */
 	function wp_startswith( $haystack, $needle ) {
+		if ( ! $haystack || ! is_string( $haystack ) ) {
+			return false;
+		}
 		return 0 === strpos( $haystack, $needle );
 	}
 endif;