diff --git a/include/kf/Semaphore.h b/include/kf/Semaphore.h
index ee9c3b2..cf63c0d 100644
--- a/include/kf/Semaphore.h
+++ b/include/kf/Semaphore.h
@@ -21,10 +21,10 @@ namespace kf
             return &m_semaphore;
         }
 
-        NTSTATUS wait(_In_opt_ PLARGE_INTEGER timeout = nullptr)
+        NTSTATUS wait(_In_opt_ const LARGE_INTEGER* timeout = nullptr)
         {
             ASSERT(KeGetCurrentIrql() <= APC_LEVEL);
-            return KeWaitForSingleObject(&m_semaphore, Executive, KernelMode, false, timeout);
+            return KeWaitForSingleObject(&m_semaphore, Executive, KernelMode, false, const_cast<LARGE_INTEGER*>(timeout));
         }
 
         void release(LONG adjustment = 1)
diff --git a/test/CMakeLists.txt b/test/CMakeLists.txt
index 50de854..ec9140c 100644
--- a/test/CMakeLists.txt
+++ b/test/CMakeLists.txt
@@ -63,6 +63,7 @@ wdk_add_driver(kf-test WINVER NTDDI_WIN10 STL
     AutoSpinLockTest.cpp
     EResourceSharedLockTest.cpp
     RecursiveAutoSpinLockTest.cpp
+    SemaphoreTest.cpp
     UStringBuilderTest.cpp
     USimpleStringTest.cpp
 )
diff --git a/test/SemaphoreTest.cpp b/test/SemaphoreTest.cpp
new file mode 100644
index 0000000..f89fd79
--- /dev/null
+++ b/test/SemaphoreTest.cpp
@@ -0,0 +1,132 @@
+#include "pch.h"
+#include <kf/Semaphore.h>
+
+SCENARIO("kf::Semaphore")
+{
+    constexpr LARGE_INTEGER kOneMillisecond{ .QuadPart = -10'000LL }; // 1ms
+    constexpr LARGE_INTEGER kZeroTimeout{};
+
+    GIVEN("A semaphore with count = 1 and limit = 1")
+    {
+        kf::Semaphore sem(1, 1);
+
+        WHEN("Trying to acquire should succeed immediately")
+        {
+            THEN("Thread doesn't wait")
+            {
+                REQUIRE(STATUS_SUCCESS == sem.wait(&kZeroTimeout));
+            }
+        }
+
+        WHEN("Acquiring twice should deplete the count and then timeout")
+        {
+            REQUIRE(STATUS_SUCCESS == sem.wait(&kZeroTimeout));
+
+            THEN("Second wait times out")
+            {
+                REQUIRE(STATUS_TIMEOUT == sem.wait(&kOneMillisecond));
+            }
+        }
+
+        WHEN("After depleting, release allows acquiring again")
+        {
+            REQUIRE(STATUS_SUCCESS == sem.wait(&kZeroTimeout));
+            REQUIRE(STATUS_TIMEOUT == sem.wait(&kOneMillisecond));
+
+            sem.release();
+
+            THEN("Wait succeeds after release")
+            {
+                REQUIRE(STATUS_SUCCESS == sem.wait(&kZeroTimeout));
+            }
+        }
+    }
+
+    GIVEN("A semaphore with count = 0 and limit = 1")
+    {
+        kf::Semaphore sem(0, 1);
+
+        WHEN("Trying to acquire should timeout")
+        {
+            THEN("Wait fails with timeout")
+            {
+                REQUIRE(STATUS_TIMEOUT == sem.wait(&kOneMillisecond));
+            }
+        }
+
+        WHEN("Release makes next acquire succeed and then timeout again")
+        {
+            sem.release();
+
+            THEN("First wait succeeds immediately and subsequent wait times out")
+            {
+                REQUIRE(STATUS_SUCCESS == sem.wait(&kZeroTimeout));
+                REQUIRE(STATUS_TIMEOUT == sem.wait(&kOneMillisecond));
+            }
+        }
+    }
+
+    GIVEN("A semaphore with count = 1000 and limit = 1000")
+    {
+        kf::Semaphore sem(1000, 1000);
+
+        WHEN("Acquiring up to count succeeds, extra wait times out")
+        {
+            for (int i = 0; i < 1000; ++i)
+            {
+                REQUIRE(STATUS_SUCCESS == sem.wait(&kZeroTimeout));
+            }
+
+            THEN("Next wait times out")
+            {
+                REQUIRE(STATUS_TIMEOUT == sem.wait(&kOneMillisecond));
+            }
+        }
+
+        WHEN("Releasing after depletion allows acquire to succeed")
+        {
+            for (int i = 0; i < 1000; ++i)
+            {
+                REQUIRE(STATUS_SUCCESS == sem.wait(&kZeroTimeout));
+            }
+            REQUIRE(STATUS_TIMEOUT == sem.wait(&kOneMillisecond));
+
+            sem.release();
+
+            THEN("Wait succeeds after release")
+            {
+                REQUIRE(STATUS_SUCCESS == sem.wait(&kZeroTimeout));
+            }
+        }
+    }
+
+    GIVEN("A semaphore with count = 0, limit = 2 and multi-adjust release")
+    {
+        kf::Semaphore sem(0, 2);
+
+        WHEN("Release with adjustment 2")
+        {
+            sem.release(2);
+
+            THEN("Two immediate acquires succeed, third times out")
+            {
+                REQUIRE(STATUS_SUCCESS == sem.wait(&kZeroTimeout));
+                REQUIRE(STATUS_SUCCESS == sem.wait(&kZeroTimeout));
+                REQUIRE(STATUS_TIMEOUT == sem.wait(&kOneMillisecond));
+            }
+        }
+
+        WHEN("Multiple single releases allow multiple acquires")
+        {
+            sem.release();
+            sem.release();
+
+            THEN("Two immediate acquires succeed, next times out")
+            {
+                REQUIRE(STATUS_SUCCESS == sem.wait(&kZeroTimeout));
+                REQUIRE(STATUS_SUCCESS == sem.wait(&kZeroTimeout));
+                REQUIRE(STATUS_TIMEOUT == sem.wait(&kOneMillisecond));
+            }
+        }
+    }
+}
\ No newline at end of file