diff --git a/batched/dense/impl/KokkosBatched_Iamax_Serial_Impl.hpp b/batched/dense/impl/KokkosBatched_Iamax_Serial_Impl.hpp
index c357e65bdc..9c0f99028b 100644
--- a/batched/dense/impl/KokkosBatched_Iamax_Serial_Impl.hpp
+++ b/batched/dense/impl/KokkosBatched_Iamax_Serial_Impl.hpp
@@ -24,11 +24,12 @@
 namespace KokkosBatched {
 
 template <typename XViewType>
-KOKKOS_INLINE_FUNCTION int SerialIamax::invoke(const XViewType &x) {
+KOKKOS_INLINE_FUNCTION typename XViewType::size_type SerialIamax::invoke(const XViewType &x) {
   static_assert(Kokkos::is_view_v<XViewType>, "KokkosBatched::iamax: XViewType is not a Kokkos::View.");
-  if (x.extent(0) <= 0) return -1;
-  if (x.extent(0) == 1) return 0;
-  return KokkosBatched::Impl::SerialIamaxInternal::invoke(x.extent(0), x.data(), x.stride(0));
+  if (x.extent(0) <= 1) return 0;
+  using size_type  = typename XViewType::size_type;
+  using value_type = typename XViewType::non_const_value_type;
+  return KokkosBatched::Impl::SerialIamaxInternal::invoke<size_type, value_type>(x.extent(0), x.data(), x.stride(0));
 }
 
 }  // namespace KokkosBatched
diff --git a/batched/dense/impl/KokkosBatched_Iamax_Serial_Internal.hpp b/batched/dense/impl/KokkosBatched_Iamax_Serial_Internal.hpp
index 7b7d3f251d..89aed299ae 100644
--- a/batched/dense/impl/KokkosBatched_Iamax_Serial_Internal.hpp
+++ b/batched/dense/impl/KokkosBatched_Iamax_Serial_Internal.hpp
@@ -30,19 +30,20 @@ namespace Impl {
 /// ========================
 
 struct SerialIamaxInternal {
-  template <typename ValueType>
-  KOKKOS_INLINE_FUNCTION static int invoke(const int n, const ValueType *KOKKOS_RESTRICT x, const int xs0);
+  template <typename IndexType, typename ValueType>
+  KOKKOS_INLINE_FUNCTION static IndexType invoke(const int n, const ValueType *KOKKOS_RESTRICT x, const int xs0);
 };
 
-template <typename ValueType>
-KOKKOS_INLINE_FUNCTION int SerialIamaxInternal::invoke(const int n, const ValueType *KOKKOS_RESTRICT x, const int xs0) {
+template <typename IndexType, typename ValueType>
+KOKKOS_INLINE_FUNCTION IndexType SerialIamaxInternal::invoke(const int n, const ValueType *KOKKOS_RESTRICT x,
+                                                             const int xs0) {
   using ats      = typename Kokkos::ArithTraits<ValueType>;
   using RealType = typename ats::mag_type;
 
-  RealType amax = Kokkos::abs(x[0 * xs0]);
-  int imax      = 0;
+  RealType amax  = Kokkos::abs(x[0 * xs0]);
+  IndexType imax = 0;
 
-  for (int i = 1; i < n; ++i) {
+  for (IndexType i = 1; i < static_cast<IndexType>(n); ++i) {
     const RealType abs_x_i = Kokkos::abs(x[i * xs0]);
     if (abs_x_i > amax) {
       amax = abs_x_i;
diff --git a/batched/dense/src/KokkosBatched_Iamax.hpp b/batched/dense/src/KokkosBatched_Iamax.hpp
index cb37e6c23a..c388ca943f 100644
--- a/batched/dense/src/KokkosBatched_Iamax.hpp
+++ b/batched/dense/src/KokkosBatched_Iamax.hpp
@@ -28,13 +28,13 @@ namespace KokkosBatched {
 /// \param X [in]: Input view type
 ///
 /// \return The index of the first element having maximum absolute value
-/// As well as Blas, this returns -1 (0 in Fortran) for an empty vector
+/// As well as Blas, this returns 0 (0 in Fortran) for an empty vector
 /// No nested parallel_for is used inside of the function.
 ///
 
 struct SerialIamax {
   template <typename XViewType>
-  KOKKOS_INLINE_FUNCTION static int invoke(const XViewType &x);
+  KOKKOS_INLINE_FUNCTION static typename XViewType::size_type invoke(const XViewType &x);
 };
 }  // namespace KokkosBatched
 
diff --git a/batched/dense/unit_test/Test_Batched_SerialIamax.hpp b/batched/dense/unit_test/Test_Batched_SerialIamax.hpp
index 85bf1b95ad..38e9e78e04 100644
--- a/batched/dense/unit_test/Test_Batched_SerialIamax.hpp
+++ b/batched/dense/unit_test/Test_Batched_SerialIamax.hpp
@@ -39,7 +39,7 @@ struct Functor_BatchedSerialIamax {
   void operator()(const int k) const {
     auto sub_x = Kokkos::subview(m_x, k, Kokkos::ALL());
     auto iamax = KokkosBatched::SerialIamax::invoke(sub_x);
-    m_r(k)     = iamax;
+    m_r(k)     = static_cast<int>(iamax);
   }
 
   inline void run() {
@@ -198,9 +198,9 @@ void impl_test_batched_iamax(const std::size_t N, const std::size_t BlkSize) {
   // Reference
   auto h_iamax_ref = Kokkos::create_mirror_view(iamax_ref);
   if (BlkSize == 0) {
-    // As well as blas, we store -1 (0 in Fortran) for empty matrix
+    // As well as blas, we store 0 (0 in Fortran) for empty matrix
     for (std::size_t k = 0; k < N; k++) {
-      h_iamax_ref(k) = -1;
+      h_iamax_ref(k) = 0;
     }
   } else {
     auto h_A = Kokkos::create_mirror_view_and_copy(Kokkos::HostSpace(), A);