diff --git a/src/security/tpm/back-end-file.cpp b/src/security/tpm/back-end-file.cpp
index 7c836d2..a560fad 100644
--- a/src/security/tpm/back-end-file.cpp
+++ b/src/security/tpm/back-end-file.cpp
@@ -129,7 +129,7 @@
     return keyHandle;
   }
   catch (const std::runtime_error& e) {
-    BOOST_THROW_EXCEPTION(Error(std::string("Cannot write key to disk: ") + e.what()));
+    BOOST_THROW_EXCEPTION(Error("Cannot write key to disk: "s + e.what()));
   }
 }