diff --git a/FEXCore/unittests/APITests/AtomicBitmapAllocator.cpp b/FEXCore/unittests/APITests/AtomicBitmapAllocator.cpp
new file mode 100644
index 000000000..ddeeef3e7
--- /dev/null
+++ b/FEXCore/unittests/APITests/AtomicBitmapAllocator.cpp
@@ -0,0 +1,94 @@
+// SPDX-License-Identifier: MIT
+#include <catch2/catch_all.hpp>
+#include <unordered_set>
+
+#include "Utils/atomic_segmented_bitmap_allocator.h"
+
+TEST_CASE("Single") {
+  FEXCore::Utils::atomic_segmented_bitmap_allocator alloc {};
+  alloc.init(4096);
+  alloc.init(162 * 1024);
+  alloc.init(1280 * 1024);
+}
+
+TEST_CASE("Single - tiny") {
+  FEXCore::Utils::atomic_segmented_bitmap_allocator alloc {};
+  alloc.init(4096);
+  std::map<void*, uint64_t> hits {};
+  for (size_t i = 0; i < 256; ++i) {
+    auto ptr = alloc.allocate(16);
+    CHECK(ptr != nullptr);
+
+    // Count any potential duplicate hits.
+    hits[ptr] += 1;
+  }
+
+  // Ensure all hits aren't duplicated.
+  for (auto hit : hits) {
+    CHECK(hit.second == 1);
+  }
+
+  // Final allocation should fail.
+  CHECK(alloc.allocate(16) == nullptr);
+}
+
+TEST_CASE("Single - tiny failover") {
+  FEXCore::Utils::atomic_segmented_bitmap_allocator alloc {};
+
+  // Should give 6400 + 128 + 0 allocation counts with the default buckets.
+  const size_t allocation_size = 164 * 1024;
+  alloc.init(allocation_size);
+
+  std::map<void*, uint64_t> hits {};
+  std::unordered_set<ssize_t> hit_buckets;
+
+  void* ptr {};
+  while ((ptr = alloc.allocate(16)) != nullptr) {
+    // Count any potential duplicate hits.
+    hits[ptr] += 1;
+    hit_buckets.emplace(alloc.find_bucket_index(ptr));
+  }
+
+  // Ensure all hits aren't duplicated.
+  for (auto hit : hits) {
+    CHECK(hit.second == 1);
+  }
+
+  // Ensure at least two buckets were hit.
+  size_t buckets {};
+  size_t total_memory {};
+  for (auto index : hit_buckets) {
+    REQUIRE(index != -1);
+    buckets++;
+
+    const auto granule_information = alloc.get_granule_information(index);
+    REQUIRE(granule_information.has_value());
+    CHECK(granule_information->free == 0);
+    total_memory += granule_information->allocated * granule_information->granule_size;
+  }
+
+  CHECK(buckets > 1);
+  CHECK(total_memory == allocation_size);
+
+  // Walk all the allocations and free them.
+  for (auto hit : hits) {
+    alloc.free(hit.first, 16);
+  }
+}
+
+TEST_CASE("Single - tiny - free") {
+  FEXCore::Utils::atomic_segmented_bitmap_allocator alloc {};
+
+  std::vector<void*> values {};
+  values.resize(256);
+  alloc.init(4096);
+
+  for (size_t i = 0; i < 256; ++i) {
+    auto ptr = alloc.allocate(16);
+    values[i] = ptr;
+  }
+
+  for (size_t i = 0; i < 256; ++i) {
+    alloc.free(values[i], 16);
+  }
+}