diff --git a/service/storage_proxy.cc b/service/storage_proxy.cc
index 4e9f09462d..4eaa7bbcbb 100644
--- a/service/storage_proxy.cc
+++ b/service/storage_proxy.cc
@@ -3323,7 +3323,10 @@ public:
                     }
                     exec->on_read_resolved();
                 } else { // digest mismatch
-                    if (is_datacenter_local(exec->_cl)) {
+                    // Do not optimize cross-dc repair if read_timestamp is missing (or just negative)
+                    // We're interested in reads that happen within write_timeout of a write,
+                    // and comparing a timestamp that is too far causes int overflow (#5556)
+                    if (is_datacenter_local(exec->_cl) && exec->_cmd->read_timestamp >= api::timestamp_type(0)) {
                         auto write_timeout = exec->_proxy->_db.local().get_config().write_request_timeout_in_ms() * 1000;
                         auto delta = int64_t(digest_resolver->last_modified()) - int64_t(exec->_cmd->read_timestamp);
                         if (std::abs(delta) <= write_timeout) {