diff --git a/src/gpu/VirtualFluids_GPU/Output/FileWriter.cpp b/src/gpu/VirtualFluids_GPU/Output/FileWriter.cpp
index 06694ca352249ed2ec0907504f21c66a3164fc32..5c293118e7583b38ab700fffa317febabdeb64a1 100644
--- a/src/gpu/VirtualFluids_GPU/Output/FileWriter.cpp
+++ b/src/gpu/VirtualFluids_GPU/Output/FileWriter.cpp
@@ -184,7 +184,7 @@ void FileWriter::writeUnstrucuredGridLT(std::shared_ptr<Parameter> para, int lev
     //nodedatanames.push_back("sendNodes");
     //nodedatanames.push_back("sparseIndex");
 
-    uint firstTurbNode = nodedatanames.size();
+    uint firstTurbNode = (uint) nodedatanames.size();
     if (para->getCalcTurbulenceIntensity()) {
         nodedatanames.push_back("vxx");
         nodedatanames.push_back("vyy");