diff --git a/std/outbuffer.d b/std/outbuffer.d
index d09bc36e21b..774fa475dd8 100644
--- a/std/outbuffer.d
+++ b/std/outbuffer.d
@@ -310,10 +310,7 @@ class OutBuffer
     {
         version (Win64)
         {
-            va_list ap;
-            ap = cast(va_list)&format;
-            ap += format.sizeof;
-            vprintf(format, ap);
+            vprintf(format, _argptr);
         }
         else version (X86_64)
         {
diff --git a/std/stream.d b/std/stream.d
index 9f686027602..fdf6cc412e9 100644
--- a/std/stream.d
+++ b/std/stream.d
@@ -1164,10 +1164,7 @@ class Stream : InputStream, OutputStream {
   // returns number of bytes written
   version (Win64)
   size_t printf(const(char)[] format, ...) {
-    va_list ap;
-    ap = cast(va_list) &format;
-    ap += format.sizeof;
-    return vprintf(format, ap);
+    return vprintf(format, _argptr);
   }
   else version (X86_64)
   size_t printf(const(char)[] format, ...) {