diff --git a/gutenberg.php b/gutenberg.php
index a72000fd626edc..d69dcc00911bc2 100644
--- a/gutenberg.php
+++ b/gutenberg.php
@@ -11,7 +11,7 @@
  */
 
 ### BEGIN AUTO-GENERATED DEFINES
-define( 'GUTENBERG_DEVELOPMENT_MODE', true );
+defined( 'GUTENBERG_DEVELOPMENT_MODE' ) or define( 'GUTENBERG_DEVELOPMENT_MODE', true );
 ### END AUTO-GENERATED DEFINES
 
 gutenberg_pre_init();