diff --git a/Src/Particle/AMReX_BinIterator.H b/Src/Particle/AMReX_BinIterator.H
index 00f378e9508..c654f7ea513 100644
--- a/Src/Particle/AMReX_BinIterator.H
+++ b/Src/Particle/AMReX_BinIterator.H
@@ -22,7 +22,7 @@ constexpr bool IsParticleTileData (Args...) {
 template <typename T>
 struct BinIterator
 {
-    using index_type = unsigned int;
+    using index_type = int;
 
     using const_pointer_type = typename std::conditional<IsParticleTileData<T>(),
         T,
diff --git a/Src/Particle/AMReX_DenseBins.H b/Src/Particle/AMReX_DenseBins.H
index 5ff9ecdc23f..e289d7b22b8 100644
--- a/Src/Particle/AMReX_DenseBins.H
+++ b/Src/Particle/AMReX_DenseBins.H
@@ -29,7 +29,7 @@ namespace BinPolicy
 template <typename T>
 struct DenseBinIteratorFactory
 {
-    using index_type = unsigned int;
+    using index_type = int;
 
     using const_pointer_type = typename std::conditional<IsParticleTileData<T>(),
         T,
@@ -77,7 +77,7 @@ class DenseBins
 public:
 
     using BinIteratorFactory = DenseBinIteratorFactory<T>;
-    using index_type = unsigned int;
+    using index_type = int;
 
     using const_pointer_type = typename std::conditional<IsParticleTileData<T>(),
         T,
diff --git a/Src/Particle/AMReX_SparseBins.H b/Src/Particle/AMReX_SparseBins.H
index 6ec80a0a831..65bcf5256b8 100644
--- a/Src/Particle/AMReX_SparseBins.H
+++ b/Src/Particle/AMReX_SparseBins.H
@@ -14,7 +14,7 @@ template <typename T>
 struct SparseBinIteratorFactory
 {
 
-    using index_type = unsigned int;
+    using index_type = int;
 
     using const_pointer_type = typename std::conditional<IsParticleTileData<T>(),
         T,
@@ -33,7 +33,7 @@ struct SparseBinIteratorFactory
         : m_bins_ptr(bins.dataPtr()),
           m_offsets_ptr(offsets.dataPtr()),
           m_permutation_ptr(permutation.dataPtr()),
-          m_items(items), m_num_bins(bins.size())
+          m_items(items), m_num_bins(int(bins.size()))
     {}
 
     [[nodiscard]] AMREX_GPU_HOST_DEVICE
@@ -97,7 +97,7 @@ public:
 
     using BinIteratorFactory = SparseBinIteratorFactory<T>;
     using bin_type = IntVect;
-    using index_type = unsigned int;
+    using index_type = int;
 
     using const_pointer_type = typename std::conditional<IsParticleTileData<T>(),
         T,