diff --git a/Misc/ACKS b/Misc/ACKS
index 23a5205..afc42ef 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -409,6 +409,7 @@
 Lou Kates
 Hiroaki Kawai
 Sebastien Keim
+Ryan Kelly
 Robert Kern
 Randall Kern
 Magnus Kessler
diff --git a/Misc/NEWS b/Misc/NEWS
index 768f5a4..6bf21ac 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -29,6 +29,9 @@
 Library
 -------
 
+- Issue #6915: Under Windows, os.listdir() didn't release the Global
+  Interpreter Lock around all system calls.  Original patch by Ryan Kelly.
+
 - Issue #3757: thread-local objects now support cyclic garbage collection.
   Thread-local objects involved in reference cycles will be deallocated
   timely by the cyclic GC, even if the underlying thread is still running.
diff --git a/Modules/posixmodule.c b/Modules/posixmodule.c
index d0d68c9..5237f14 100644
--- a/Modules/posixmodule.c
+++ b/Modules/posixmodule.c
@@ -2127,7 +2127,9 @@
             free(wnamebuf);
             return NULL;
         }
+        Py_BEGIN_ALLOW_THREADS
         hFindFile = FindFirstFileW(wnamebuf, &wFileData);
+        Py_END_ALLOW_THREADS
         if (hFindFile == INVALID_HANDLE_VALUE) {
             int error = GetLastError();
             if (error == ERROR_FILE_NOT_FOUND) {
@@ -2197,7 +2199,9 @@
     if ((d = PyList_New(0)) == NULL)
         return NULL;
 
+    Py_BEGIN_ALLOW_THREADS
     hFindFile = FindFirstFile(namebuf, &FileData);
+    Py_END_ALLOW_THREADS
     if (hFindFile == INVALID_HANDLE_VALUE) {
         int error = GetLastError();
         if (error == ERROR_FILE_NOT_FOUND)