diff --git a/rostests/kmtests/include/kmt_platform.h b/rostests/kmtests/include/kmt_platform.h
index f8f2e4a1d32..8cb2fe5bd0b 100644
--- a/rostests/kmtests/include/kmt_platform.h
+++ b/rostests/kmtests/include/kmt_platform.h
@@ -56,6 +56,7 @@ typedef ULONG LOGICAL, *PLOGICAL;
 #define RtlCopyMemoryNonTemporal                RtlCopyMemory
 #define RtlPrefetchMemoryNonTemporal(s, l)
 #define ExRaiseStatus                           RtlRaiseStatus
+#define KmtIsCheckedBuild                       FALSE
 #endif /* defined KMT_EMULATE_KERNEL */
 
 #endif /* defined KMT_USER_MODE */
diff --git a/rostests/kmtests/kmtest_drv/testlist.c b/rostests/kmtests/kmtest_drv/testlist.c
index e8b0dc725ea..2fb2f0078e4 100644
--- a/rostests/kmtests/kmtest_drv/testlist.c
+++ b/rostests/kmtests/kmtest_drv/testlist.c
@@ -59,6 +59,7 @@ KMT_TESTFUNC Test_RtlIntSafe;
 KMT_TESTFUNC Test_RtlMemory;
 KMT_TESTFUNC Test_RtlRegistry;
 KMT_TESTFUNC Test_RtlSplayTree;
+KMT_TESTFUNC Test_RtlUnicodeString;
 KMT_TESTFUNC Test_ZwAllocateVirtualMemory;
 KMT_TESTFUNC Test_ZwCreateSection;
 KMT_TESTFUNC Test_ZwMapViewOfSection;
@@ -117,6 +118,7 @@ const KMT_TEST TestList[] =
     { "RtlMemoryKM",                        Test_RtlMemory },
     { "RtlRegistryKM",                      Test_RtlRegistry },
     { "RtlSplayTreeKM",                     Test_RtlSplayTree },
+    { "RtlUnicodeStringKM",                 Test_RtlUnicodeString },
     { "ZwAllocateVirtualMemory",            Test_ZwAllocateVirtualMemory },
     { "ZwCreateSection",                    Test_ZwCreateSection },
     { "ZwMapViewOfSection",                 Test_ZwMapViewOfSection },
diff --git a/rostests/kmtests/ntos_fsrtl/FsRtlExpression.c b/rostests/kmtests/ntos_fsrtl/FsRtlExpression.c
index eb45b7b0475..48d09d3357e 100644
--- a/rostests/kmtests/ntos_fsrtl/FsRtlExpression.c
+++ b/rostests/kmtests/ntos_fsrtl/FsRtlExpression.c
@@ -184,10 +184,6 @@ static VOID FsRtlIsNameInExpressionTest()
         UNICODE_STRING Expression;
         UNICODE_STRING Name;
 
-        /* Don't run Tests which are known to assert in checked builds */
-        if (KmtIsCheckedBuild && Tests[i].AssertsInChecked)
-            continue;
-
         RtlInitUnicodeString(&Expression, Tests[i].Expression);
         RtlInitUnicodeString(&Name, Tests[i].Name);
 
diff --git a/rostests/kmtests/rtl/RtlUnicodeString.c b/rostests/kmtests/rtl/RtlUnicodeString.c
index d17d08f4cff..0c4a9db8913 100644
--- a/rostests/kmtests/rtl/RtlUnicodeString.c
+++ b/rostests/kmtests/rtl/RtlUnicodeString.c
@@ -87,7 +87,7 @@ TestFindCharInUnicodeString(VOID)
     Status = RtlFindCharInUnicodeString(7, &String, &Chars4, &Position);
     ok_eq_hex(Status, STATUS_SUCCESS);
     ok_eq_uint(Position, 22);
-    
+
     /* Show that Position is USHORT */
     LongPosition = 0x55555555;
     Status = RtlFindCharInUnicodeString(8, &String, &String, (PUSHORT)&LongPosition);
@@ -116,7 +116,7 @@ TestFindCharInUnicodeString(VOID)
         Status = RtlFindCharInUnicodeString(0, NULL, &String, &Position);
     KmtEndSeh(STATUS_ACCESS_VIOLATION);
     ok_eq_uint(Position, 0);
-    
+
     /* NULL for SearchString and invalid flags */
     Position = 123;
     KmtStartSeh()
@@ -150,7 +150,7 @@ TestFindCharInUnicodeString(VOID)
     KmtEndSeh(STATUS_ACCESS_VIOLATION);
     ok_eq_uint(Position, 0);
 #endif
-    
+
     /* NULL for MatchString and invalid flags */
     Position = 123;
     KmtStartSeh()
@@ -173,7 +173,87 @@ TestFindCharInUnicodeString(VOID)
 #endif
 }
 
+static
+VOID
+TestUpcaseUnicodeString(VOID)
+{
+    NTSTATUS Status;
+    UNICODE_STRING Lower;
+    UNICODE_STRING Upper;
+    PWCHAR Buffer;
+
+    Buffer = KmtAllocateGuarded(sizeof(WCHAR));
+
+    if (!KmtIsCheckedBuild)
+    {
+    RtlInitEmptyUnicodeString(&Lower, NULL, 0);
+    RtlFillMemory(&Upper, sizeof(Upper), 0x55);
+    Status = RtlUpcaseUnicodeString(&Upper, &Lower, TRUE);
+    ok_eq_hex(Status, STATUS_SUCCESS);
+    ok_eq_uint(Upper.Length, 0);
+    ok_eq_uint(Upper.MaximumLength, 0);
+    ok(Upper.Buffer != NULL, "Buffer = %p\n", Upper.Buffer);
+    RtlFreeUnicodeString(&Upper);
+
+    RtlInitEmptyUnicodeString(&Lower, Buffer, 0);
+    RtlFillMemory(&Upper, sizeof(Upper), 0x55);
+    Status = RtlUpcaseUnicodeString(&Upper, &Lower, TRUE);
+    ok_eq_hex(Status, STATUS_SUCCESS);
+    ok_eq_uint(Upper.Length, 0);
+    ok_eq_uint(Upper.MaximumLength, 0);
+    ok(Upper.Buffer != NULL, "Buffer = %p\n", Upper.Buffer);
+    RtlFreeUnicodeString(&Upper);
+
+    RtlInitEmptyUnicodeString(&Lower, Buffer, sizeof(WCHAR));
+    Buffer[0] = UNICODE_NULL;
+    RtlFillMemory(&Upper, sizeof(Upper), 0x55);
+    Status = RtlUpcaseUnicodeString(&Upper, &Lower, TRUE);
+    ok_eq_hex(Status, STATUS_SUCCESS);
+    ok_eq_uint(Upper.Length, 0);
+    ok_eq_uint(Upper.MaximumLength, 0);
+    ok(Upper.Buffer != NULL, "Buffer = %p\n", Upper.Buffer);
+    RtlFreeUnicodeString(&Upper);
+    }
+
+    RtlInitEmptyUnicodeString(&Lower, Buffer, sizeof(WCHAR));
+    Lower.Length = sizeof(WCHAR);
+    Buffer[0] = UNICODE_NULL;
+    RtlFillMemory(&Upper, sizeof(Upper), 0x55);
+    Status = RtlUpcaseUnicodeString(&Upper, &Lower, TRUE);
+    ok_eq_hex(Status, STATUS_SUCCESS);
+    ok_eq_uint(Upper.Length, sizeof(WCHAR));
+    ok_eq_uint(Upper.MaximumLength, sizeof(WCHAR));
+    ok(Upper.Buffer != NULL, "Buffer = %p\n", Upper.Buffer);
+    ok_eq_hex(Upper.Buffer[0], UNICODE_NULL);
+    RtlFreeUnicodeString(&Upper);
+
+    RtlInitEmptyUnicodeString(&Lower, Buffer, sizeof(WCHAR));
+    Lower.Length = sizeof(WCHAR);
+    Buffer[0] = 'a';
+    RtlFillMemory(&Upper, sizeof(Upper), 0x55);
+    Status = RtlUpcaseUnicodeString(&Upper, &Lower, TRUE);
+    ok_eq_hex(Status, STATUS_SUCCESS);
+    ok_eq_uint(Upper.Length, sizeof(WCHAR));
+    ok_eq_uint(Upper.MaximumLength, sizeof(WCHAR));
+    ok(Upper.Buffer != NULL, "Buffer = %p\n", Upper.Buffer);
+    ok_eq_hex(Upper.Buffer[0], 'A');
+    RtlFreeUnicodeString(&Upper);
+
+    RtlInitUnicodeString(&Lower, L"a");
+    RtlFillMemory(&Upper, sizeof(Upper), 0x55);
+    Status = RtlUpcaseUnicodeString(&Upper, &Lower, TRUE);
+    ok_eq_hex(Status, STATUS_SUCCESS);
+    ok_eq_uint(Upper.Length, sizeof(WCHAR));
+    ok_eq_uint(Upper.MaximumLength, sizeof(WCHAR));
+    ok(Upper.Buffer != NULL, "Buffer = %p\n", Upper.Buffer);
+    ok_eq_hex(Upper.Buffer[0], 'A');
+    RtlFreeUnicodeString(&Upper);
+
+    KmtFreeGuarded(Buffer);
+}
+
 START_TEST(RtlUnicodeString)
 {
     TestFindCharInUnicodeString();
+    TestUpcaseUnicodeString();
 }