diff --git a/include/olm/list.hh b/include/olm/list.hh
index 6906c87..5bdaca3 100644
--- a/include/olm/list.hh
+++ b/include/olm/list.hh
@@ -99,9 +99,9 @@ public:
             return *this;
         }
         T * this_pos = _data;
-        T * const other_pos = other._data;
+        const T * other_pos = other._data;
         while (other_pos != other._end) {
-            *this_pos = *other;
+            *this_pos = *other_pos;
             ++this_pos;
             ++other_pos;
         }
diff --git a/src/session.cpp b/src/session.cpp
index 6cc73e3..d66ccc0 100644
--- a/src/session.cpp
+++ b/src/session.cpp
@@ -437,7 +437,7 @@ void olm::Session::describe(char *describe_buffer, size_t buflen) {
 
     size = snprintf(
         describe_buffer, remaining,
-        "sender chain index: %d ", ratchet.sender_chain[0].chain_key.index
+        "sender chain index: %lu ", ratchet.sender_chain[0].chain_key.index
     );
     CHECK_SIZE_AND_ADVANCE;
 
@@ -447,7 +447,7 @@ void olm::Session::describe(char *describe_buffer, size_t buflen) {
     for (size_t i = 0; i < ratchet.receiver_chains.size(); ++i) {
         size = snprintf(
             describe_buffer, remaining,
-            " %d", ratchet.receiver_chains[i].chain_key.index
+            " %lu", ratchet.receiver_chains[i].chain_key.index
         );
         CHECK_SIZE_AND_ADVANCE;
     }
@@ -458,7 +458,7 @@ void olm::Session::describe(char *describe_buffer, size_t buflen) {
     for (size_t i = 0; i < ratchet.skipped_message_keys.size(); ++i) {
         size = snprintf(
             describe_buffer, remaining,
-            " %d", ratchet.skipped_message_keys[i].message_key.index
+            " %lu", ratchet.skipped_message_keys[i].message_key.index
         );
         CHECK_SIZE_AND_ADVANCE;
     }