diff --git a/Phys/lwtnnParser/lwtnnParser/NNLayerConfig.h b/Phys/lwtnnParser/lwtnnParser/NNLayerConfig.h
index 6443613ab0838e8fcd133e2d65a08505306f2507..42bcc730c0cf6a4817195772b7873a84c1bdb89e 100644
--- a/Phys/lwtnnParser/lwtnnParser/NNLayerConfig.h
+++ b/Phys/lwtnnParser/lwtnnParser/NNLayerConfig.h
@@ -77,9 +77,9 @@ namespace lwt {
   // graph node configuration
   struct NodeConfig {
     enum class Type { INPUT, INPUT_SEQUENCE, FEED_FORWARD, CONCATENATE, SEQUENCE, TIME_DISTRIBUTED };
-    Type                type;
-    std::vector<size_t> sources;
-    int                 index; // input node size, or layer number
+    Type                     type;
+    std::vector<std::size_t> sources;
+    int                      index; // input node size, or layer number
   };
 } // namespace lwt