diff --git a/ports/win32/sys_arch.c b/ports/win32/sys_arch.c
index 97ee665..a157019 100644
--- a/ports/win32/sys_arch.c
+++ b/ports/win32/sys_arch.c
@@ -72,8 +72,8 @@ static void sys_win_rand_init(void)
     DWORD err = GetLastError();
     LWIP_PLATFORM_DIAG(("CryptAcquireContext failed with error %d, trying to create NEWKEYSET", (int)err));
     if(!CryptAcquireContext(&hcrypt, NULL, NULL, PROV_RSA_FULL, CRYPT_NEWKEYSET)) {
-      err = GetLastError();
       char errbuf[128];
+      err = GetLastError();
       snprintf(errbuf, sizeof(errbuf), "CryptAcquireContext failed with error %d", (int)err);
       LWIP_UNUSED_ARG(err);
       LWIP_ASSERT(errbuf, 0);