diff --git a/source/texk/web2c/luatexdir/dvi/dvigen.w b/source/texk/web2c/luatexdir/dvi/dvigen.w
index 9033899..11e86fa 100644
--- a/source/texk/web2c/luatexdir/dvi/dvigen.w
+++ b/source/texk/web2c/luatexdir/dvi/dvigen.w
@@ -1191,10 +1191,11 @@ void write_out(halfword p)
         if (callback_id > 0) {
             lua_retval = run_callback(callback_id, "S->S", s, &ss);
             if ((lua_retval == true) && (ss != NULL))
-                s = ss;
+	      { xfree(s); s = ss; }
         }
     }
     tprint(s);
+    xfree(s);
     print_ln();
     flush_list(def_ref);
     if (j == 18) {
diff --git a/source/texk/web2c/luatexdir/tex/expand.w b/source/texk/web2c/luatexdir/tex/expand.w
index 4ca243c..419e0c2 100644
--- a/source/texk/web2c/luatexdir/tex/expand.w
+++ b/source/texk/web2c/luatexdir/tex/expand.w
@@ -344,7 +344,7 @@ void manufacture_csname(void)
     } else {
         cur_cs = null_cs;       /* the list is empty */
     }
-    xfree(ss->s);
+    free_lstring(ss);
     flush_list(r);
     if (eq_type(cur_cs) == undefined_cs_cmd) {
         eq_define(cur_cs, relax_cmd, too_big_char);     /* N.B.: The |save_stack| might change */
diff --git a/source/texk/web2c/luatexdir/tex/filename.w b/source/texk/web2c/luatexdir/tex/filename.w
index e984868..c969fb9 100644
--- a/source/texk/web2c/luatexdir/tex/filename.w
+++ b/source/texk/web2c/luatexdir/tex/filename.w
@@ -107,6 +107,7 @@ static void end_name(void)
         cur_string[area_delimiter] = '\0';
         cur_length = (unsigned) strlen((char *) cur_string);
         cur_area = make_string();
+	xfree(cur_string);
         cur_length = (unsigned) strlen((char *) s);
         cur_string = s;
     }
@@ -119,6 +120,7 @@ static void end_name(void)
         cur_string[l] = '\0';
         cur_length = (unsigned) strlen((char *) cur_string);
         cur_name = make_string();
+	xfree(cur_string);
         cur_length = (unsigned) strlen((char *) s);
         cur_string = s;
         cur_ext = make_string();
diff --git a/source/texk/web2c/luatexdir/tex/primitive.w b/source/texk/web2c/luatexdir/tex/primitive.w
index abaac09..5617031 100644
--- a/source/texk/web2c/luatexdir/tex/primitive.w
+++ b/source/texk/web2c/luatexdir/tex/primitive.w
@@ -389,6 +389,7 @@ static halfword insert_id(halfword p, const unsigned char *j, unsigned int l)
         append_char(*k);
     cs_text(p) = make_string();
     cur_length = saved_cur_length;
+    xfree(cur_string);
     cur_string = saved_cur_string;
     cur_string_size = saved_cur_string_size;
     incr(cs_count);
diff --git a/source/texk/web2c/luatexdir/tex/stringpool.h b/source/texk/web2c/luatexdir/tex/stringpool.h
index 5a4b868..a55cdac 100644
--- a/source/texk/web2c/luatexdir/tex/stringpool.h
+++ b/source/texk/web2c/luatexdir/tex/stringpool.h
@@ -115,6 +115,7 @@ extern void reset_cur_string(void);
 
 #  define restore_cur_string(u) if (u!=0) {                   \
         unsigned l = (unsigned)str_length(u);		      \
+	xfree(cur_string);                                  \
         reset_cur_string();                                 \
         str_room(l);                                        \
         memcpy(cur_string, str_string(u),l);                \