diff --git a/common/utils/windows-compat.h b/common/utils/windows-compat.h
index 658c1d8bc..6d84a39a3 100644
--- a/common/utils/windows-compat.h
+++ b/common/utils/windows-compat.h
@@ -1,5 +1,5 @@
 /* nbdkit
- * Copyright (C) 2020 Red Hat Inc.
+ * Copyright (C) 2020-2022 Red Hat Inc.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
@@ -85,6 +85,12 @@ struct sockaddr_un
 #define ESHUTDOWN ECONNABORTED
 #endif
 
+/* Windows uses non-standard names for shutdown(how). */
+#ifndef SHUT_WR
+#define SHUT_WR SD_SEND
+#define SHUT_RDWR SD_BOTH
+#endif
+
 /* This generated function translates Winsock errors into errno codes. */
 extern int translate_winsock_error (const char *fn, int err);
 
diff --git a/filters/blocksize-policy/policy.c b/filters/blocksize-policy/policy.c
index f7cff2f11..7e6f2a968 100644
--- a/filters/blocksize-policy/policy.c
+++ b/filters/blocksize-policy/policy.c
@@ -43,6 +43,7 @@
 
 #include "ispowerof2.h"
 #include "rounding.h"
+#include "windows-compat.h"
 
 /* Block size constraints configured on the command line (0 = unset). */
 static uint32_t config_minimum;