diff --git a/unit_tests/test_alltoall.cpp b/unit_tests/test_alltoall.cpp
index 61397734..fcda51aa 100644
--- a/unit_tests/test_alltoall.cpp
+++ b/unit_tests/test_alltoall.cpp
@@ -51,8 +51,8 @@ TYPED_TEST(Alltoall, 1D_contig) {
   Kokkos::parallel_reduce(
       rv.extent(0),
       KOKKOS_LAMBDA(const int &i, int &lsum) {
-        const int src = i / nContrib;                      // who sent this data
-        const int j   = rank * nContrib + (i % nContrib);  // what index i was at the source
+        const int src = i / nContrib;         // who sent this data
+        const int j   = i - rank * nContrib;  // what index i was at the source
         lsum += rv(i) != src + j;
       },
       errs);
@@ -80,8 +80,8 @@ TYPED_TEST(Alltoall, 1D_inplace_contig) {
   Kokkos::parallel_reduce(
       rv.extent(0),
       KOKKOS_LAMBDA(const int &i, int &lsum) {
-        const int src = i / nContrib;                      // who sent this data
-        const int j   = rank * nContrib + (i % nContrib);  // what index i was at the source
+        const int src = i / nContrib;         // who sent this data
+        const int j   = i - rank * nContrib;  // what index i was at the source
         lsum += rv(i) != src + j;
       },
       errs);