diff --git a/log.c b/log.c
index 163bef96..7540a881 100644
--- a/log.c
+++ b/log.c
@@ -264,10 +264,7 @@ static void iterator_vprintf_nl(struct log_output_iterator *it, int level, struc
   assert(current_iterator);
   log_start_line(it, level);
   whence_prefix(it, whence);
-  va_list ap1;
-  va_copy(ap1, ap);
-  vxprintf(it->xpf, fmt, ap1);
-  va_end(ap1);
+  vxprintf(it->xpf, fmt, ap);
   log_end_line(it, level);
 }
 
@@ -300,7 +297,10 @@ void serval_vlogf(int level, struct __sourceloc whence, const char *fmt, va_list
 	  if (is_log_available(&it)) {
 	    current_iterator = ⁢
 	    print_newdate(&it);
-	    iterator_vprintf_nl(&it, level, whence, fmt, ap);
+	    va_list ap1;
+	    va_copy(ap1, ap);
+	    iterator_vprintf_nl(&it, level, whence, fmt, ap1);
+	    va_end(ap1);
 	    log_flush(&it);
 	    current_iterator = NULL;
 	  }
diff --git a/xprintf.c b/xprintf.c
index 2696793d..ee2b8708 100644
--- a/xprintf.c
+++ b/xprintf.c
@@ -105,14 +105,20 @@ void _cx_vprintf_mallocbuf(void *context, const char *fmt, va_list ap)
   if (mb->current) {
     if (mb->current + 1 >= mb->buffer + mb->size)
       grow_mallocbuf(mb, 1024);
-    int n = vsnprintf(mb->current, mb->buffer + mb->size - mb->current, fmt, ap);
+    va_list ap1;
+    va_copy(ap1, ap);
+    int n = vsnprintf(mb->current, mb->buffer + mb->size - mb->current, fmt, ap1);
+    va_end(ap1);
     char *newcurrent = mb->current + n;
     char *end = mb->buffer + mb->size;
     if (newcurrent < end)
       mb->current = newcurrent;
     else {
       grow_mallocbuf(mb, newcurrent - end + 1);
-      n = vsnprintf(mb->current, mb->buffer + mb->size - mb->current, fmt, ap);
+      va_list ap1;
+      va_copy(ap1, ap);
+      n = vsnprintf(mb->current, mb->buffer + mb->size - mb->current, fmt, ap1);
+      va_end(ap1);
       char *newcurrent = mb->current + n;
       char *end = mb->buffer + mb->size;
       if (newcurrent < end)