diff --git a/Dotenv.php b/Dotenv.php
index 897ad577bdf417ea41b7a01a731c42cb4d08950b..5d63a82c63c952665784304db43c9b3efcd63187 100644
--- a/Dotenv.php
+++ b/Dotenv.php
@@ -99,7 +99,7 @@ final class Dotenv {
       if (!empty($prompt) && $this->io->isInteractive()) {
         $value = $this->io->ask($prompt . ': ');
       }
-      if ($value === NULL) {
+      if ($value === FALSE) {
         $value = $default;
       }
       $this->put($key, $value, TRUE);