diff --git a/reader.c b/reader.c
index 0260aaa..0884a02 100644
--- a/reader.c
+++ b/reader.c
@@ -590,11 +590,15 @@ static void set_placeholder(reader_state_t *state, value_t place, value_t value)
 
 static void finalize_placeholders(reader_state_t *state)
 {
-  for (bool changed = true; changed; changed = false)
+  bool changed = true;
+
+  /* We're done when no placeholders link to other placeholders. */
+  while (changed)
   {
-    /* On each cycle, placeholder cycles/lists should come one link closer to self or actual value.
-     * Self-links indicate cycles and are replaced with UNDEFINED.
-     * We're done when no placeholders link to other placeholders. */
+    changed = false;
+
+    /* Resolve one level of placeholder-to-placeholder links.
+    * Self-links indicate cycles and are replaced with UNDEFINED. */
     for (value_t item = state->ref_alist.value; !is_nil(item); item = _CDDR(item))
     {
       if (_CADR(item) == item)