diff --git a/src/bias/PBMetaD.cpp b/src/bias/PBMetaD.cpp
index 3f7c4b1b8d..f407c1fcc8 100644
--- a/src/bias/PBMetaD.cpp
+++ b/src/bias/PBMetaD.cpp
@@ -633,6 +633,7 @@ PBMetaD::PBMetaD(const ActionOptions& ao):
   parse("SELECTOR", selector_);
   if(selector_.length()>0) {
     do_select_ = true;
+    select_value_ = 0; // set defalt value or it might be not initialized if the user does not pass SELECTOR_ID
     parse("SELECTOR_ID", select_value_);
   }