diff --git a/FWCore/ParameterSet/src/ParameterSet.cc b/FWCore/ParameterSet/src/ParameterSet.cc
index 0ebb5f328bccd..2061982506eea 100644
--- a/FWCore/ParameterSet/src/ParameterSet.cc
+++ b/FWCore/ParameterSet/src/ParameterSet.cc
@@ -507,7 +507,7 @@ namespace edm {
       if (useAll || b->second.isTracked()) {
         size += 2;
         size += b->first.size();
-        size += sizeof(ParameterSetID) * b->second.vpset().size();
+        size += sizeof(ParameterSetID) * b->second.size();
       }
     }
 
diff --git a/FWCore/ParameterSet/src/VParameterSetEntry.cc b/FWCore/ParameterSet/src/VParameterSetEntry.cc
index 199833bf494e8..7c4f8e4fccb34 100644
--- a/FWCore/ParameterSet/src/VParameterSetEntry.cc
+++ b/FWCore/ParameterSet/src/VParameterSetEntry.cc
@@ -98,7 +98,9 @@ namespace edm {
     return theVPSet_->at(i);
   }
 
-  std::vector<ParameterSet>::size_type VParameterSetEntry::size() const { return vpset().size(); }
+  std::vector<ParameterSet>::size_type VParameterSetEntry::size() const {
+    return theIDs_ ? theIDs_->size() : (theVPSet_ ? vpset().size() : 0);
+  }
 
   void VParameterSetEntry::registerPsetsAndUpdateIDs() {
     fillVPSet();