diff --git a/virtualSensor.cpp b/virtualSensor.cpp
index ce429f6..25c127c 100644
--- a/virtualSensor.cpp
+++ b/virtualSensor.cpp
@@ -154,6 +154,7 @@
     }
 
     symbols.add_constants();
+    symbols.add_package(vecopsPackage);
     expression.register_symbol_table(symbols);
 
     /* parser from exprtk */