diff --git a/sexp_format.c b/sexp_format.c
index d051943645a734de90aa7c043e8268b14095b80f..2480613cc4cb86d9d1d98805664b944700c18640 100644
--- a/sexp_format.c
+++ b/sexp_format.c
@@ -82,10 +82,10 @@ int
 sexp_format(struct nettle_buffer *buffer, const char *format, ...)
 {
   va_list args;
-  va_start(args, format);
-
   unsigned nesting = 0;
   
+  va_start(args, format);
+
   for (;;)
     switch (*format++)
       {