diff --git a/winsup/cygwin/fhandler/base.cc b/winsup/cygwin/fhandler/base.cc
index b2738cf20..9b49ec7b9 100644
--- a/winsup/cygwin/fhandler/base.cc
+++ b/winsup/cygwin/fhandler/base.cc
@@ -1728,7 +1728,8 @@ fhandler_base::utimens (const struct timespec *tvp)
 int
 fhandler_base::fsync ()
 {
-  if (!get_handle () || nohandle () || pc.isspecial ())
+  if (!get_handle () || nohandle ()
+      || (pc.isspecial () && !S_ISBLK (pc.dev.mode ())))
     {
       set_errno (EINVAL);
       return -1;
diff --git a/winsup/cygwin/release/3.4.6 b/winsup/cygwin/release/3.4.6
new file mode 100644
index 000000000..c1476ff46
--- /dev/null
+++ b/winsup/cygwin/release/3.4.6
@@ -0,0 +1,5 @@
+Bug Fixes
+---------
+
+Fix a problem that fsync returns EINVAL for block device.
+Addresses: https://cygwin.com/pipermail/cygwin/2023-January/252916.html