diff --git a/tests/other/fw/congestion-mark-strategy.cpp b/tests/other/fw/congestion-mark-strategy.cpp
index ea73d4e..3e2ccce 100644
--- a/tests/other/fw/congestion-mark-strategy.cpp
+++ b/tests/other/fw/congestion-mark-strategy.cpp
@@ -62,7 +62,7 @@
 
   if (parsed.version && *parsed.version != getStrategyName()[-1].toVersion()) {
     BOOST_THROW_EXCEPTION(std::invalid_argument(
-      "CongestionMarkStrategy does not support version " + std::to_string(*parsed.version)));
+      "CongestionMarkStrategy does not support version " + to_string(*parsed.version)));
   }
   this->setInstanceName(makeInstanceName(name, getStrategyName()));
 }