diff --git a/collection_mutation.cc b/collection_mutation.cc
index 7e1e8f253d..bdfdf664a8 100644
--- a/collection_mutation.cc
+++ b/collection_mutation.cc
@@ -261,14 +261,18 @@ collection_mutation merge(const abstract_type& type, collection_mutation_view a,
     });
 }
 
-collection_mutation
-collection_type_impl::difference(collection_mutation_view a, collection_mutation_view b) const
+collection_mutation difference(const abstract_type& type, collection_mutation_view a, collection_mutation_view b)
 {
-    return a.with_deserialized(*this, [&] (collection_mutation_view_description a_view) {
-        return b.with_deserialized(*this, [&] (collection_mutation_view_description b_view) {
+    return a.with_deserialized(type, [&] (collection_mutation_view_description a_view) {
+        return b.with_deserialized(type, [&] (collection_mutation_view_description b_view) {
+            assert(type.is_collection());
+            auto& ctype = static_cast<const collection_type_impl&>(type);
+
             collection_mutation_view_description diff;
             diff.cells.reserve(std::max(a_view.cells.size(), b_view.cells.size()));
-            auto key_type = name_comparator();
+
+            auto key_type = ctype.name_comparator();
+
             auto it = b_view.cells.begin();
             for (auto&& c : a_view.cells) {
                 while (it != b_view.cells.end() && key_type->less(it->first, c.first)) {
@@ -284,7 +288,7 @@ collection_type_impl::difference(collection_mutation_view a, collection_mutation
             if (a_view.tomb > b_view.tomb) {
                 diff.tomb = a_view.tomb;
             }
-            return diff.serialize(*this);
+            return diff.serialize(type);
         });
     });
 }
diff --git a/collection_mutation.hh b/collection_mutation.hh
index b328b448a4..879c27d03e 100644
--- a/collection_mutation.hh
+++ b/collection_mutation.hh
@@ -111,3 +111,5 @@ public:
 };
 
 collection_mutation merge(const abstract_type&, collection_mutation_view, collection_mutation_view);
+
+collection_mutation difference(const abstract_type&, collection_mutation_view, collection_mutation_view);
diff --git a/mutation_partition.cc b/mutation_partition.cc
index bf43d0cd42..411eb0da3e 100644
--- a/mutation_partition.cc
+++ b/mutation_partition.cc
@@ -1835,8 +1835,8 @@ row row::difference(const schema& s, column_kind kind, const row& other) const
                     r.append_cell(c.first, c.second.copy(*cdef.type));
                 }
             } else {
-                auto ct = static_pointer_cast<const collection_type_impl>(s.column_at(kind, c.first).type);
-                auto diff = ct->difference(c.second.as_collection_mutation(), it->second.as_collection_mutation());
+                auto diff = ::difference(*s.column_at(kind, c.first).type,
+                        c.second.as_collection_mutation(), it->second.as_collection_mutation());
                 if (!static_cast<collection_mutation_view>(diff).is_empty()) {
                     r.append_cell(c.first, std::move(diff));
                 }
diff --git a/types/collection.hh b/types/collection.hh
index ce314c2023..505626eff7 100644
--- a/types/collection.hh
+++ b/types/collection.hh
@@ -53,7 +53,6 @@ public:
     static bytes pack(BytesViewIterator start, BytesViewIterator finish, int elements, cql_serialization_format sf);
     virtual bytes to_value(collection_mutation_view_description mut, cql_serialization_format sf) const = 0;
     bytes to_value(collection_mutation_view mut, cql_serialization_format sf) const;
-    collection_mutation difference(collection_mutation_view a, collection_mutation_view b) const;
     virtual void serialize(const void* value, bytes::iterator& out, cql_serialization_format sf) const = 0;
     virtual data_value deserialize(bytes_view v, cql_serialization_format sf) const = 0;
     data_value deserialize_value(bytes_view v, cql_serialization_format sf) const {