diff --git a/libisofs/ecma119_tree.c b/libisofs/ecma119_tree.c
index 9e517ad..afc3450 100644
--- a/libisofs/ecma119_tree.c
+++ b/libisofs/ecma119_tree.c
@@ -592,6 +592,9 @@ int mangle_single_dir(Ecma119Image *img, Ecma119Node *dir, int max_file_len,
     nchildren = dir->info.dir->nchildren;
     children = dir->info.dir->children;
 
+    if (nchildren <= 0)
+        return ISO_SUCCESS; /* nothing to do */
+
     /* a hash table will temporary hold the names, for fast searching */
     ret = iso_htable_create((nchildren * 100) / 80, iso_str_hash,
                             (compare_function_t)strcmp, &table);
diff --git a/libisofs/util_htable.c b/libisofs/util_htable.c
index 1a0a8e5..5e55273 100644
--- a/libisofs/util_htable.c
+++ b/libisofs/util_htable.c
@@ -322,9 +322,10 @@ int iso_htable_create(size_t size, hash_funtion_t hash,
 {
     IsoHTable *t;
     
-    if (table == NULL) {
-        return ISO_OUT_OF_MEM;
-    }
+    if (size <= 0)
+        return ISO_WRONG_ARG_VALUE;
+    if (table == NULL)
+        return ISO_NULL_POINTER;
     
     t = malloc(sizeof(IsoHTable));
     if (t == NULL) {