diff --git a/src/include/pg_config.h.in b/src/include/pg_config.h.in
index 132462ac09..9b107e27f7 100644
--- a/src/include/pg_config.h.in
+++ b/src/include/pg_config.h.in
@@ -668,6 +668,9 @@
 /* Define to select Win32-style semaphores. */
 #undef USE_WIN32_SEMAPHORES
 
+/* Define to select Win32-style shared memory. */
+#undef USE_WIN32_SHARED_MEMORY
+
 /* Number of bits in a file offset, on hosts where this is settable. */
 #undef _FILE_OFFSET_BITS