diff --git a/taglib/toolkit/tbytevectorlist.cpp b/taglib/toolkit/tbytevectorlist.cpp
index 0088087f..d915148b 100644
--- a/taglib/toolkit/tbytevectorlist.cpp
+++ b/taglib/toolkit/tbytevectorlist.cpp
@@ -70,7 +70,8 @@ ByteVectorList::~ByteVectorList() = default;
 ByteVectorList::ByteVectorList(const ByteVectorList &l) :
   List<ByteVector>(l)
 {
-  *d = *l.d;
+  // Uncomment if d is used, d.get() is nullptr and *d behavior undefined
+  // *d = *l.d;
 }
 
 ByteVectorList::ByteVectorList(std::initializer_list<ByteVector> init) :
@@ -84,7 +85,8 @@ ByteVectorList &ByteVectorList::operator=(const ByteVectorList &l)
     return *this;
 
   List<ByteVector>::operator=(l);
-  *d = *l.d;
+  // Uncomment if d is used, d.get() is nullptr and *d behavior undefined
+  // *d = *l.d;
   return *this;
 }
 
diff --git a/taglib/toolkit/tstringlist.cpp b/taglib/toolkit/tstringlist.cpp
index aa6acf64..893522fe 100644
--- a/taglib/toolkit/tstringlist.cpp
+++ b/taglib/toolkit/tstringlist.cpp
@@ -59,7 +59,8 @@ StringList::StringList() = default;
 StringList::StringList(const StringList &l) :
   List<String>(l)
 {
-  *d = *l.d;
+  // Uncomment if d is used, d.get() is nullptr and *d behavior undefined
+  // *d = *l.d;
 }
 
 StringList::StringList(std::initializer_list<String> init) :
@@ -73,7 +74,8 @@ StringList &StringList::operator=(const StringList &l)
     return *this;
 
   List<String>::operator=(l);
-  *d = *l.d;
+  // Uncomment if d is used, d.get() is nullptr and *d behavior undefined
+  // *d = *l.d;
   return *this;
 }