diff --git a/CHANGES b/CHANGES
index 3194fbdbf3..c0f62195b3 100644
--- a/CHANGES
+++ b/CHANGES
@@ -1,3 +1,12 @@
+6.2.0-dev.305 | 2024-01-03 09:38:17 +0000
+
+  * Avoid extra copies in threading_field_to_data (Dominik Charousset)
+
+    Passing the `broker::data` paramter for `threading_field_to_data` by
+    value forces copies. However, the function only needs const access to
+    its parameter. Hence, taking the parameter as const-ref is the logical
+    choice and avoids unnecessary copies of individual data fields.
+
 6.2.0-dev.302 | 2024-01-02 11:13:17 -0700
 
   * smb: Fix &read_expire not in effect due to &default=string_set() usage (Arne Welzel, Corelight)
diff --git a/VERSION b/VERSION
index 05df0a0187..f94329c18e 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-6.2.0-dev.302
+6.2.0-dev.305
diff --git a/src/broker/Data.cc b/src/broker/Data.cc
index 4440bc6f5d..aa7928add8 100644
--- a/src/broker/Data.cc
+++ b/src/broker/Data.cc
@@ -1154,13 +1154,17 @@ broker::data threading_field_to_data(const threading::Field* f) {
     return broker::vector({name, secondary, type, subtype, optional});
 }
 
-threading::Field* data_to_threading_field(broker::data d) {
+threading::Field* data_to_threading_field(const broker::data& d) {
     if ( ! holds_alternative<broker::vector>(d) )
         return nullptr;
 
     auto& v = get<broker::vector>(d);
+
+    if ( v.size() < 5 )
+        return nullptr;
+
     auto name = get_if<std::string>(&v[0]);
-    auto secondary = v[1];
+    const auto& secondary = v[1];
     auto type = get_if<broker::count>(&v[2]);
     auto subtype = get_if<broker::count>(&v[3]);
     auto optional = get_if<broker::boolean>(&v[4]);
diff --git a/src/broker/Data.h b/src/broker/Data.h
index 2b91d404f6..4bdfe8e82c 100644
--- a/src/broker/Data.h
+++ b/src/broker/Data.h
@@ -101,7 +101,7 @@ broker::data threading_field_to_data(const threading::Field* f);
  * @return a pointer to a new zeek::threading::Value or a nullptr if the conversion was not
  * possible.
  */
-threading::Field* data_to_threading_field(broker::data d);
+threading::Field* data_to_threading_field(const broker::data& d);
 
 /**
  * A Zeek value which wraps a Broker data value.