cygwin also doesn't have qsort_r
diff --git a/src/util.c b/src/util.c
index 3985825..f9d37e4 100644
--- a/src/util.c
+++ b/src/util.c
@@ -612,7 +612,7 @@ void git__qsort_r(
#if defined(__MINGW32__) || defined(AMIGA) || \
defined(__OpenBSD__) || defined(__NetBSD__) || \
defined(__gnu_hurd__) || defined(__ANDROID_API__) || \
- defined(__sun) || \
+ defined(__sun) || defined(__CYGWIN__) || \
(__GLIBC__ == 2 && __GLIBC_MINOR__ < 8)
git__insertsort_r(els, nel, elsize, NULL, cmp, payload);
#elif defined(GIT_WIN32)