diff --git a/CondFormats/PhysicsToolsObjects/interface/MVAComputer.h b/CondFormats/PhysicsToolsObjects/interface/MVAComputer.h
index 2189275bbc063..1a3753e59a41e 100644
--- a/CondFormats/PhysicsToolsObjects/interface/MVAComputer.h
+++ b/CondFormats/PhysicsToolsObjects/interface/MVAComputer.h
@@ -28,6 +28,16 @@ namespace PhysicsTools {
 
     class BitSet {
     public:
+      // help that poor ROOT to copy bitsets... (workaround)
+      BitSet &operator=(const BitSet &other) {
+        store = other.store;
+        bitsInLast = other.bitsInLast;
+        return *this;
+      }
+      BitSet(const BitSet &other) = default;
+      BitSet() = default;
+      ~BitSet() = default;
+
       std::vector<unsigned char> store;
       unsigned int bitsInLast;
 
@@ -61,6 +71,7 @@ namespace PhysicsTools {
       inline Variable() {}
       inline Variable(const std::string &name) : name(name) {}
       inline ~Variable() {}
+      Variable &operator=(const Variable &other) = default;
 
       std::string name;
 
diff --git a/PhysicsTools/MVAComputer/interface/Variable.h b/PhysicsTools/MVAComputer/interface/Variable.h
index ea74807050bea..ff7040d48d4e6 100644
--- a/PhysicsTools/MVAComputer/interface/Variable.h
+++ b/PhysicsTools/MVAComputer/interface/Variable.h
@@ -132,6 +132,7 @@ namespace PhysicsTools {
     inline Variable() {}
     inline Variable(const Variable &orig) : name(orig.name), flags(orig.flags) {}
     inline Variable(AtomicId name, Flags flags = FLAG_NONE) : name(name), flags(flags) {}
+    Variable &operator=(const Variable &other) = default;
 
     const AtomicId getName() const { return name; }
     Flags getFlags() const { return flags; }