diff --git a/src/backend/storage/ipc/dsm_impl.c b/src/backend/storage/ipc/dsm_impl.c
index 7122c4a..e96b5d6 100644
--- a/src/backend/storage/ipc/dsm_impl.c
+++ b/src/backend/storage/ipc/dsm_impl.c
@@ -681,6 +681,12 @@ dsm_impl_windows(dsm_op op, dsm_handle handle, Size request_size,
 #endif
 		size_low = (DWORD) request_size;
 
+		/*
+		 * We can't rely on CreateFileMapping() to the set error code to 0 on
+		 * success
+		 */
+		SetLastError(0);
+
 		hmap = CreateFileMapping(INVALID_HANDLE_VALUE,	/* Use the pagefile */
 								 NULL,	/* Default security attrs */
 								 PAGE_READWRITE,		/* Memory is read/write */