, known_namespaces[i].plugin_handles[j]);
                                printf("closing plugin %i at class %s, file %s\n", known_namespaces[i].plugin_handles[j], known_namespaces[i].opened_classes[j], known_namespaces[i].opened_files[j]);
                                glite_jppsbe_close_file(ctx, known_namespaces[i].file_handles[j]);
-                               known_namespaces[i].opened_classes[j] = NULL;
-                               known_namespaces[i].opened_files[j] = NULL;
+                               if (known_namespaces[i].opened_classes[j]){
+                                       free(known_namespaces[i].opened_classes[j]);
+                                       known_namespaces[i].opened_classes[j] = NULL;
+                               }
+                               if (known_namespaces[i].opened_files[j]){
+                                       free(known_namespaces[i].opened_files[j]);
+                                       known_namespaces[i].opened_files[j] = NULL;
+                               }
                                known_namespaces[i].plugin_handles[j] = NULL;
                                known_namespaces[i].file_handles[j] = NULL;
                        }