diff --git a/CMakeLists.txt b/CMakeLists.txt
index 48daddd2..b758b843 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -3,7 +3,6 @@ cmake_minimum_required(VERSION 2.8...3.5 FATAL_ERROR)
 project(isle CXX)
 
 option(ISLE_BUILD_APP "Build ISLE.EXE application" ON)
-option(BUILD_COMPAT "Compatibility for modern compilers" OFF)
 
 add_library(lego1 SHARED
   LEGO1/act1state.cpp
@@ -227,7 +226,3 @@ if (MSVC)
   set(CMAKE_SHARED_LINKER_FLAGS_RELWITHDEBINFO "/incremental:no /debug")
   set(CMAKE_SHARED_LINKER_FLAGS_MINSIZEREL "/incremental:no")
 endif()
-
-if (BUILD_COMPAT)
-  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /D \"ISLE_COMPAT\"")
-endif()
diff --git a/LEGO1/compat.h b/LEGO1/compat.h
index 496fa4db..d415fe1b 100644
--- a/LEGO1/compat.h
+++ b/LEGO1/compat.h
@@ -11,4 +11,17 @@
 #define COMPAT_CONST
 #endif
 
-#endif // ISLECOMPAT_H
\ No newline at end of file
+#define MSVC420_VERSION 1020
+
+// STL compatibility.
+#if defined(_MSC_VER) && (_MSC_VER <= MSVC420_VERSION)
+#include <STL.H>
+#else
+#include <algorithm>
+#include <list>
+using namespace std;
+template <class T>
+using List = list<T>;
+#endif
+
+#endif // ISLECOMPAT_H
diff --git a/LEGO1/mxnotificationmanager.cpp b/LEGO1/mxnotificationmanager.cpp
index 66034563..3ed34f2f 100644
--- a/LEGO1/mxnotificationmanager.cpp
+++ b/LEGO1/mxnotificationmanager.cpp
@@ -5,8 +5,8 @@
 #include "mxparam.h"
 #include "mxtypes.h"
 
+#include "compat.h"
 #include "decomp.h"
-#include "stlcompat.h"
 
 DECOMP_SIZE_ASSERT(MxNotification, 0x8);
 // Can't use DECOMP_SIZE_ASSERT due to STL type size changes.
diff --git a/LEGO1/mxnotificationmanager.h b/LEGO1/mxnotificationmanager.h
index 06c11dc8..e313510b 100644
--- a/LEGO1/mxnotificationmanager.h
+++ b/LEGO1/mxnotificationmanager.h
@@ -5,7 +5,7 @@
 #include "mxcriticalsection.h"
 #include "mxtypes.h"
 
-#include "stlcompat.h"
+#include "compat.h"
 
 class MxNotification
 {
diff --git a/LEGO1/stlcompat.h b/LEGO1/stlcompat.h
deleted file mode 100644
index 5607590f..00000000
--- a/LEGO1/stlcompat.h
+++ /dev/null
@@ -1,14 +0,0 @@
-#ifndef STLCOMPAT_H
-#define STLCOMPAT_H
-
-#ifndef ISLE_COMPAT
-#include <STL.H>
-#else
-#include <algorithm>
-#include <list>
-using namespace std;
-template <class T>
-using List = list<T>;
-#endif
-
-#endif // STLCOMPAT_H