diff --git a/src/lib/subs/pr.c b/src/lib/subs/pr.c
index 15c58b85..b2b04395 100644
--- a/src/lib/subs/pr.c
+++ b/src/lib/subs/pr.c
@@ -367,6 +367,9 @@ prmptrd(char *prompt, char *buf, int size)
      */
     CANT_HAPPEN(player->aborted);
 
+    if (CANT_HAPPEN(!prompt))
+	prompt = "? ";
+
     pr_id(player, C_FLUSH, "%s\n", prompt);
     if ((r = recvclient(buf, size)) < 0)
 	return r;
@@ -396,6 +399,9 @@ uprmptrd(char *prompt, char *buf, int size)
     /* See prmptrd() */
     CANT_HAPPEN(player->aborted);
 
+    if (CANT_HAPPEN(!prompt))
+	prompt = "? ";
+
     pr_id(player, C_FLUSH, "%s\n", prompt);
     if ((r = recvclient(buf, size)) < 0)
 	return r;