diff --git a/ext/standard/tests/general_functions/gh20727.phpt b/ext/standard/tests/general_functions/gh20727.phpt
new file mode 100644
index 0000000000000..f5d8f69dadf96
--- /dev/null
+++ b/ext/standard/tests/general_functions/gh20727.phpt
@@ -0,0 +1,11 @@
+--TEST--
+GH-20727 (User code can run after module request shutdown via the output layer)
+--FILE--
+<?php
+putenv('foo=baz');
+header_register_callback(function(){
+    var_dump(putenv('foo=bar'));
+});
+?>
+--EXPECT--
+bool(true)
diff --git a/main/main.c b/main/main.c
index f190eab3d094f..7c45782807f18 100644
--- a/main/main.c
+++ b/main/main.c
@@ -1997,16 +1997,16 @@ void php_request_shutdown(void *dummy)
 		zend_unset_timeout();
 	} zend_end_try();
 
-	/* 5. Call all extensions RSHUTDOWN functions */
-	if (PG(modules_activated)) {
-		zend_deactivate_modules();
-	}
-
-	/* 6. Shutdown output layer (send the set HTTP headers, cleanup output handlers, etc.) */
+	/* 5. Shutdown output layer (send the set HTTP headers, cleanup output handlers, etc.) */
 	zend_try {
 		php_output_deactivate();
 	} zend_end_try();
 
+	/* 6. Call all extensions RSHUTDOWN functions */
+	if (PG(modules_activated)) {
+		zend_deactivate_modules();
+	}
+
 	/* 7. Free shutdown functions */
 	if (PG(modules_activated)) {
 		php_free_shutdown_functions();