diff -ruN readline-8.3.orig/input.c readline-8.3/input.c
--- readline-8.3.orig/input.c	2025-05-02 15:29:05.000000000 +0200
+++ readline-8.3/input.c	2025-12-24 09:42:16.297387295 +0100
@@ -261,13 +261,16 @@
   input = 0;
   tty = fileno (rl_instream);
 
-  /* Move this up here to give it first shot, but it can't set chars_avail */
+  /* Move this up here to give it first shot, but it can't set chars_avail,
+     so we assume a single character is available. */
   /* XXX - need rl_chars_available_hook? */
   if (rl_input_available_hook)
     {
       result = (*rl_input_available_hook) ();
       if (result == 0)
         result = -1;
+      else
+        chars_avail = 1;
     }
 
 #if defined (HAVE_PSELECT) || defined (HAVE_SELECT)
@@ -285,6 +288,7 @@
 #endif
       if (result <= 0)
 	return 0;	/* Nothing to read. */
+      result = -1;    /* there is something, so check how many chars below */
     }
 #endif
 
diff -ruN readline-8.3.orig/patchlevel readline-8.3/patchlevel
--- readline-8.3.orig/patchlevel	2020-05-21 20:22:40.000000000 +0200
+++ readline-8.3/patchlevel	2025-12-24 09:42:16.297387295 +0100
@@ -1,3 +1,3 @@
 # Do not edit -- exists only for use by patch
 
-0
+1