diff --git a/src/sphere/sphere.cpp b/src/sphere/sphere.cpp
index b21d7ea8f6426f96143137aa124dd138183e728b..448002d20c1dde9881768d52e5a63d3436f20688 100644
--- a/src/sphere/sphere.cpp
+++ b/src/sphere/sphere.cpp
@@ -37,8 +37,8 @@ void sphere(string config_file, string data_file, string output_path) {
     printf("FILE: %s\n", ex.what());
     exit(1);
   }
-  sconf->write_formatted(output_path + "c_OEDFB");
-  sconf->write_binary(output_path + "c_TEDF");
+  sconf->write_formatted(output_path + "/c_OEDFB");
+  sconf->write_binary(output_path + "/c_TEDF");
   GeometryConfiguration *gconf = NULL;
   try {
     gconf = GeometryConfiguration::from_legacy(data_file);