diff --git a/ext/standard/basic_functions.c b/ext/standard/basic_functions.c
index cc5b587c04c8..12a06fadf1ae 100644
--- a/ext/standard/basic_functions.c
+++ b/ext/standard/basic_functions.c
@@ -774,6 +774,9 @@ PHP_FUNCTION(putenv)
 		zend_argument_value_error(1, "must have a valid syntax");
 		RETURN_THROWS();
 	}
+	if (UNEXPECTED(EG(flags) & EG_FLAGS_IN_RESOURCE_SHUTDOWN)) {
+		RETURN_FALSE;
+	}
 
 	pe.putenv_string = zend_strndup(setting, setting_len);
 	if ((p = strchr(setting, '='))) {
diff --git a/ext/standard/tests/streams/gh20656.phpt b/ext/standard/tests/streams/gh20656.phpt
new file mode 100644
index 000000000000..764d8a4406b6
--- /dev/null
+++ b/ext/standard/tests/streams/gh20656.phpt
@@ -0,0 +1,17 @@
+--TEST--
+GH-20656 (HashTable use-after-destroy in function table via stream wrapper magic __call() with nested redeclaration)
+--FILE--
+<?php
+class Loader {
+    function stream_open() {
+        return true;
+    }
+    function __call($m, $a) {
+        $map[$obj] = putenv("LA=Gx$g_lang");
+        function __call($m, $a) {}
+    }
+}
+stream_wrapper_register('abc', 'Loader');
+require 'abc://';
+?>
+--EXPECT--