diff --git a/lib/internal/v8_prof_polyfill.js b/lib/internal/v8_prof_polyfill.js
index b4c025d50e..34cd10337f 100644
--- a/lib/internal/v8_prof_polyfill.js
+++ b/lib/internal/v8_prof_polyfill.js
@@ -76,7 +76,7 @@ function readline() {
     const bytes = fs.readSync(fd, buf, 0, buf.length);
     line += dec.write(buf.slice(0, bytes));
     if (line.length === 0) {
-      return false;
+      return '';
     }
   }
 }