diff --git a/ext/standard/basic_functions.c b/ext/standard/basic_functions.c
index 99d92af167f0e..d2a99fccc95fe 100644
--- a/ext/standard/basic_functions.c
+++ b/ext/standard/basic_functions.c
@@ -849,6 +849,7 @@ PHP_FUNCTION(putenv)
 #endif
 		RETURN_TRUE;
 	} else {
+		tsrm_env_unlock();
 		free(pe.putenv_string);
 		zend_string_release(pe.key);
 #ifdef PHP_WIN32