diff --git a/daemon/daemon.h b/daemon/daemon.h
index c92e1108e..6f288c172 100644
--- a/daemon/daemon.h
+++ b/daemon/daemon.h
@@ -145,10 +145,11 @@ extern void main_loop (int sock) __attribute__((noreturn));
  * NB: you don't need to prefix the string with the current command,
  * it is added automatically by the client-side RPC stubs.
  */
-extern void reply_with_error (const char *fs, ...)
-  __attribute__((format (printf,1,2)));
+extern void reply_with_error_errno (int err, const char *fs, ...)
+  __attribute__((format (printf,2,3)));
 extern void reply_with_perror_errno (int err, const char *fs, ...)
   __attribute__((format (printf,2,3)));
+#define reply_with_error(...) reply_with_error_errno(0, __VA_ARGS__)
 #define reply_with_perror(...) reply_with_perror_errno(errno, __VA_ARGS__)
 
 /* daemon functions that receive files (FileIn) should call
diff --git a/daemon/proto.c b/daemon/proto.c
index ac62a6be6..d3cf2810a 100644
--- a/daemon/proto.c
+++ b/daemon/proto.c
@@ -221,16 +221,16 @@ main_loop (int _sock)
 static void send_error (int errnum, const char *msg);
 
 void
-reply_with_error (const char *fs, ...)
+reply_with_error_errno (int err, const char *fs, ...)
 {
-  char err[GUESTFS_ERROR_LEN];
+  char buf[GUESTFS_ERROR_LEN];
   va_list args;
 
   va_start (args, fs);
-  vsnprintf (err, sizeof err, fs, args);
+  vsnprintf (buf, sizeof buf, fs, args);
   va_end (args);
 
-  send_error (0, err);
+  send_error (err, buf);
 }
 
 void