diff --git a/library/x509_csr.c b/library/x509_csr.c
index 4dec9b9..c0c7679 100644
--- a/library/x509_csr.c
+++ b/library/x509_csr.c
@@ -302,7 +302,8 @@
 }
 #endif /* POLARSSL_FS_IO */
 
-#if defined(_MSC_VER) && !defined snprintf
+#if defined(_MSC_VER) && !defined snprintf && !defined(EFIX64) && \
+    !defined(EFI32)
 #include <stdarg.h>
 
 #if !defined vsnprintf