diff --git a/src/composite.c b/src/composite.c
index 2eddda00b5d..e36e1670d8d 100644
--- a/src/composite.c
+++ b/src/composite.c
@@ -1101,6 +1101,9 @@ composition_compute_stop_pos (struct composition_it *cmp_it, ptrdiff_t charpos,
 
   /* Look for automatic compositions.  */
   start = charpos;
+  /* For the case that they set it to something weird, like nil.  */
+  if (!CHAR_TABLE_P (Vcomposition_function_table))
+    Vcomposition_function_table = Fmake_char_table (Qnil, Qnil);
   if (charpos < endpos)
     {
       /* Forward search.  */
@@ -1324,6 +1327,9 @@ composition_reseat_it (struct composition_it *cmp_it, ptrdiff_t charpos,
       Lisp_Object lgstring = Qnil;
       Lisp_Object val, elt, direction = Qnil;
 
+      /* For the case that they set it to something weird, like nil.  */
+      if (!CHAR_TABLE_P (Vcomposition_function_table))
+	Vcomposition_function_table = Fmake_char_table (Qnil, Qnil);
       val = CHAR_TABLE_REF (Vcomposition_function_table, cmp_it->ch);
       for (EMACS_INT i = 0; i < cmp_it->rule_idx; i++, val = XCDR (val))
 	continue;