diff -Nur dia2code-0.8.3/dia2code/parse_diagram.c dia2code-0.8.3.new/dia2code/parse_diagram.c
--- dia2code-0.8.3/dia2code/parse_diagram.c	2003-03-05 17:44:38.000000000 +0100
+++ dia2code-0.8.3.new/dia2code/parse_diagram.c	2007-12-13 10:36:02.000000000 +0100
@@ -490,7 +490,7 @@
     }
     implementator = find(classlist, id);
     free(id);
-    if (implementator != NULL && strlen(name) > 2) {
+    if (implementator != NULL && name != NULL && strlen(name) > 2) {
         interface = (umlclasslist) my_malloc (sizeof (umlclassnode));
         interface->key = (umlclass *) my_malloc (sizeof(umlclass));
         interface->parents = NULL;