diff --git a/Misc/NEWS b/Misc/NEWS
index d8c4ea02bb2..36bf9c35a26 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -29,6 +29,8 @@ Core and Builtins
 Library
 -------
 
+- Issue #15777: Fix a refleak in _posixsubprocess.
+
 - Issue ##665194: Update email.utils.localtime to use datetime.astimezone and
   correctly handle historic changes in UTC offsets.
 
diff --git a/Modules/_posixsubprocess.c b/Modules/_posixsubprocess.c
index b8fb72f62e6..8f0fcf20b8b 100644
--- a/Modules/_posixsubprocess.c
+++ b/Modules/_posixsubprocess.c
@@ -568,8 +568,10 @@ subprocess_fork_exec(PyObject* self, PyObject *args)
     }
 
     exec_array = _PySequence_BytesToCharpArray(executable_list);
-    if (!exec_array)
+    if (!exec_array) {
+        Py_XDECREF(gc_module);
         return NULL;
+    }
 
     /* Convert args and env into appropriate arguments for exec() */
     /* These conversions are done in the parent process to avoid allocating