diff --git a/tests/core/load_balancing/ParMetisTest.cpp b/tests/core/load_balancing/ParMetisTest.cpp
index 320315e8d86e4f9dbd8bda4c5bd0e6ea8d44aeac..0b9643961ab083a4da5a4fc886c5060eb9bc4116 100644
--- a/tests/core/load_balancing/ParMetisTest.cpp
+++ b/tests/core/load_balancing/ParMetisTest.cpp
@@ -130,7 +130,7 @@ int main( int argc, char * argv[] )
    int64_t numflag = 0;
    int64_t nparts = int64_c( partitions );
    std::vector< double > tpwgts( partitions, 1.0 / numeric_cast<double>( partitions ) );
-   std::vector< double > ubvec( ncon, 1.05 );
+   std::vector< double > ubvec( numeric_cast<size_t>(ncon), 1.05 );
    int64_t options[] = {0,0,0};
    int64_t edgecut;
    std::vector< int64_t > part( fieldSize[0] * fieldSize[1] );