diff --git a/Modules/posixmodule.c b/Modules/posixmodule.c
index 7286445..2afd5a6 100644
--- a/Modules/posixmodule.c
+++ b/Modules/posixmodule.c
@@ -6193,8 +6193,10 @@
     s1 = PyBytes_AsString(os1);
 
     err = unsetenv(s1);
-    if (err)
+    if (err) {
+        Py_DECREF(s1);
         return posix_error();
+    }
 
     /* Remove the key from posix_putenv_garbage;
      * this will cause it to be collected.  This has to