diff --git a/hist/hist/src/TH2Poly.cxx b/hist/hist/src/TH2Poly.cxx
index 009a63808bc22..1f96f43078e05 100644
--- a/hist/hist/src/TH2Poly.cxx
+++ b/hist/hist/src/TH2Poly.cxx
@@ -180,7 +180,8 @@ TH2Poly::TH2Poly(const char *name,const char *title,
 
 /////////////////////////////////////////////////////////////////////////////////
 /// Copy constructor
-TH2Poly::TH2Poly(const TH2Poly & rhs) : TH2() {
+TH2Poly::TH2Poly(const TH2Poly & rhs) : TH2(), fCells(nullptr),
+fIsEmpty(nullptr), fCompletelyInside(nullptr), fBins(nullptr) {
     rhs.Copy(*this);
 }