diff --git a/systemd_target_signal.cpp b/systemd_target_signal.cpp
index 30e5d5b..7698c0e 100644
--- a/systemd_target_signal.cpp
+++ b/systemd_target_signal.cpp
@@ -75,8 +75,8 @@
     }
 }
 
-const std::string SystemdTargetLogging::processError(const std::string& unit,
-                                                     const std::string& result)
+std::string SystemdTargetLogging::processError(const std::string& unit,
+                                               const std::string& result)
 {
     auto targetEntry = this->targetData.find(unit);
     if (targetEntry != this->targetData.end())