diff --git a/src/rgw/rgw_op.cc b/src/rgw/rgw_op.cc
index 6ddd6748a1b..223a94e29af 100644
--- a/src/rgw/rgw_op.cc
+++ b/src/rgw/rgw_op.cc
@@ -3381,7 +3381,7 @@ void RGWPutObj::execute()
    * processing any input from user in order to prohibit overwriting. */
   if (slo_info) {
     bufferlist slo_userindicator_bl;
-    ::encode("True", slo_userindicator_bl);
+    slo_userindicator_bl.append("True", 4);
     emplace_attr(RGW_ATTR_SLO_UINDICATOR, std::move(slo_userindicator_bl));
   }
 
diff --git a/src/rgw/rgw_rest_s3.cc b/src/rgw/rgw_rest_s3.cc
index 96285e258ff..7174a0a4e20 100644
--- a/src/rgw/rgw_rest_s3.cc
+++ b/src/rgw/rgw_rest_s3.cc
@@ -275,6 +275,9 @@ int RGWGetObj_ObjStore_S3::send_response_data(bufferlist& bl, off_t bl_ofs,
         if (!content_type) {
           content_type = iter->second.c_str();
         }
+      } else if (strcmp(name, RGW_ATTR_SLO_UINDICATOR) == 0) {
+        // this attr has an extra length prefix from ::encode() in prior versions
+        dump_header(s, "X-Object-Meta-Static-Large-Object", "True");
       } else if (strncmp(name, RGW_ATTR_META_PREFIX,
 			 sizeof(RGW_ATTR_META_PREFIX)-1) == 0) {
         /* User custom metadata. */
diff --git a/src/rgw/rgw_rest_swift.cc b/src/rgw/rgw_rest_swift.cc
index 6cca4f2efc2..7704d509529 100644
--- a/src/rgw/rgw_rest_swift.cc
+++ b/src/rgw/rgw_rest_swift.cc
@@ -1105,6 +1105,9 @@ static void dump_object_metadata(struct req_state * const s,
 
     if (aiter != std::end(rgw_to_http_attrs)) {
       response_attrs[aiter->second] = kv.second.c_str();
+    } else if (strcmp(name, RGW_ATTR_SLO_UINDICATOR) == 0) {
+      // this attr has an extra length prefix from ::encode() in prior versions
+      dump_header(s, "X-Object-Meta-Static-Large-Object", "True");
     } else if (strncmp(name, RGW_ATTR_META_PREFIX,
 		       sizeof(RGW_ATTR_META_PREFIX)-1) == 0) {
       name += sizeof(RGW_ATTR_META_PREFIX) - 1;