diff --git a/test/Common/UnitTest.cc b/test/Common/UnitTest.cc
index 16764985920d489ee597d777ad2848c63f3fd46a..d0b04c7e15de78a89c299833865ce52191658b14 100644
--- a/test/Common/UnitTest.cc
+++ b/test/Common/UnitTest.cc
@@ -10,7 +10,7 @@ UnitTest::UnitTest(unsigned deviceNumber)
 #if defined PMT_BUILD_POWERSENSOR3
 , powerSensor(pmt::Create("powersensor3", "/dev/ttyACM0"))
 #elif defined PMT_BUILD_NVIDIA
-, powerSensor(pmt::Create("nvidia", deviceNumber))
+, powerSensor(pmt::Create("nvidia", std::to_string(deviceNumber)))
 #elif defined MEASURE_POWER
 #error using PMT, but no valid PMT type configured
 #endif