diff --git a/src/node.c b/src/node.c
index 326d3cd..52ddc31 100644
--- a/src/node.c
+++ b/src/node.c
@@ -80,37 +80,27 @@ int iso_node_set_name(IsoNode *node, const char *name)
 {
     char *new;
 
-    /* guard against the empty string or big names... */
-    if (name[0] == '\0' || strlen(name) > 255) {
-        return ISO_WRONG_ARG_VALUE;
-    }
-
-    /* ...against "." and ".." names... */
-    if (!strcmp(name, ".") || !strcmp(name, "..")) {
-        return ISO_WRONG_ARG_VALUE;
-    }
-
-    /* ...and against names with '/' */
-    if (strchr(name, '/') != NULL) {
-        return ISO_WRONG_ARG_VALUE;
-    }
-
     if ((IsoNode*)node->parent == node) {
         /* you can't change name of the root node */
         return ISO_WRONG_ARG_VALUE;
     }
+    
+    /* check if the name is valid */
+    if (!iso_node_is_valid_name(name)) {
+        return ISO_WRONG_ARG_VALUE;
+    }
+
+    if (node->parent != NULL) {
+        /* check if parent already has a node with same name */
+        if (iso_dir_get_node(node->parent, name, NULL) == 1) {
+            return ISO_NODE_NAME_NOT_UNIQUE;
+        }
+    }
 
     new = strdup(name);
     if (new == NULL) {
         return ISO_MEM_ERROR;
     }
-    if (node->parent != NULL) {
-        /* check if parent already has a node with same name */
-        if (iso_dir_get_node(node->parent, name, NULL) == 1) {
-            free(new);
-            return ISO_NODE_NAME_NOT_UNIQUE;
-        }
-    }
     free(node->name);
     node->name = new;
     if (node->parent != NULL) {
@@ -595,6 +585,36 @@ int iso_file_get_sort_weight(IsoFile *file)
     return file->sort_weight;
 }
 
+/**
+ * Check if a given name is valid for an iso node.
+ * 
+ * @return
+ *     1 if yes, 0 if not
+ */
+int iso_node_is_valid_name(const char *name)
+{
+    /* a name can't be NULL */
+    if (name == NULL) {
+        return 0;
+    }
+
+    /* guard against the empty string or big names... */
+    if (name[0] == '\0' || strlen(name) > 255) {
+        return 0;
+    }
+
+    /* ...against "." and ".." names... */
+    if (!strcmp(name, ".") || !strcmp(name, "..")) {
+        return 0;
+    }
+
+    /* ...and against names with '/' */
+    if (strchr(name, '/') != NULL) {
+        return 0;
+    }
+    return 1;
+}
+
 int iso_node_new_root(IsoDir **root)
 {
     IsoDir *dir;
diff --git a/src/node.h b/src/node.h
index c79980c..f1787f3 100644
--- a/src/node.h
+++ b/src/node.h
@@ -107,4 +107,12 @@ struct Iso_Dir_Iter
 
 int iso_node_new_root(IsoDir **root);
 
+/**
+ * Check if a given name is valid for an iso node.
+ * 
+ * @return
+ *     1 if yes, 0 if not
+ */
+int iso_node_is_valid_name(const char *name);
+
 #endif /*LIBISO_NODE_H_*/
diff --git a/src/tree.c b/src/tree.c
index 0bbfb62..1b92585 100644
--- a/src/tree.c
+++ b/src/tree.c
@@ -56,6 +56,11 @@ int iso_tree_add_new_dir(IsoDir *parent, const char *name, IsoDir **dir)
     if (dir) {
         *dir = NULL;
     }
+    
+    /* check if the name is valid */
+    if (!iso_node_is_valid_name(name)) {
+        return ISO_WRONG_ARG_VALUE;
+    }
 
     /* find place where to insert */
     pos = &(parent->children);
@@ -140,6 +145,11 @@ int iso_tree_add_new_symlink(IsoDir *parent, const char *name,
     if (link) {
         *link = NULL;
     }
+    
+    /* check if the name is valid */
+    if (!iso_node_is_valid_name(name)) {
+        return ISO_WRONG_ARG_VALUE;
+    }
 
     /* find place where to insert */
     pos = &(parent->children);
@@ -248,6 +258,11 @@ int iso_tree_add_new_special(IsoDir *parent, const char *name, mode_t mode,
     if (special) {
         *special = NULL;
     }
+    
+    /* check if the name is valid */
+    if (!iso_node_is_valid_name(name)) {
+        return ISO_WRONG_ARG_VALUE;
+    }
 
     /* find place where to insert */
     pos = &(parent->children);