diff --git a/drivers/bus/isapnp/isapnp.c b/drivers/bus/isapnp/isapnp.c
index 7f2731b7ce4..69fbcbb9f3a 100644
--- a/drivers/bus/isapnp/isapnp.c
+++ b/drivers/bus/isapnp/isapnp.c
@@ -84,7 +84,7 @@ IsaFdoCreateDeviceIDs(
                                   LogDev->ProdId);
     if (!NT_SUCCESS(Status))
         return Status;
-    TempString.Length = (End - TempString.Buffer) * sizeof(WCHAR);
+    TempString.Length = (USHORT)((End - TempString.Buffer) * sizeof(WCHAR));
     Status = IsaPnpDuplicateUnicodeString(
         RTL_DUPLICATE_UNICODE_STRING_NULL_TERMINATE,
         &TempString,
@@ -105,7 +105,7 @@ IsaFdoCreateDeviceIDs(
                                   LogDev->ProdId);
     if (!NT_SUCCESS(Status))
         return Status;
-    TempString.Length = (End - TempString.Buffer) * sizeof(WCHAR);
+    TempString.Length = (USHORT)((End - TempString.Buffer) * sizeof(WCHAR));
     Status = IsaPnpDuplicateUnicodeString(
         RTL_DUPLICATE_UNICODE_STRING_NULL_TERMINATE,
         &TempString,
@@ -125,7 +125,7 @@ IsaFdoCreateDeviceIDs(
                                   LogDev->SerialNumber);
     if (!NT_SUCCESS(Status))
         return Status;
-    TempString.Length = (End - TempString.Buffer) * sizeof(WCHAR);
+    TempString.Length = (USHORT)((End - TempString.Buffer) * sizeof(WCHAR));
     Status = IsaPnpDuplicateUnicodeString(
         RTL_DUPLICATE_UNICODE_STRING_NULL_TERMINATE,
         &TempString,
diff --git a/drivers/bus/isapnp/pdo.c b/drivers/bus/isapnp/pdo.c
index 82dc98cf1a9..917ab4d626d 100644
--- a/drivers/bus/isapnp/pdo.c
+++ b/drivers/bus/isapnp/pdo.c
@@ -252,7 +252,7 @@ IsaPdoStartReadPort(
         PCM_PARTIAL_RESOURCE_DESCRIPTOR PartialDescriptor = &ResourceList->List[0].PartialResourceList.PartialDescriptors[i];
         if (PartialDescriptor->Type == CmResourceTypePort)
         {
-            PUCHAR ReadDataPort = (PUCHAR)PartialDescriptor->u.Port.Start.u.LowPart + 3;
+            PUCHAR ReadDataPort = ULongToPtr(PartialDescriptor->u.Port.Start.u.LowPart + 3);
             if (PartialDescriptor->u.Port.Length > 1 && !FdoExt->ReadDataPort && NT_SUCCESS(IsaHwTryReadDataPort(ReadDataPort)))
             {
                 FdoExt->ReadDataPort = ReadDataPort;