diff --git a/CMakeLists.txt b/CMakeLists.txt
index 53cfb23..c1a06fa 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -2,6 +2,8 @@ cmake_minimum_required(VERSION 3.11)
 
 project(sj4)
 
+option(SJ4_GLOBAL "Use global variables or not" OFF)
+
 file(GLOB_RECURSE SJ4CORE_SRCS lib/sj4core/**.c)
 add_library(sj4core STATIC ${SJ4CORE_SRCS})
 target_include_directories(sj4core PUBLIC include/sj4common include/sj4core)
@@ -20,6 +22,8 @@ file(GLOB_RECURSE SJ4TEST_SRCS src/sj4test/**.c)
 add_executable(sj4test ${SJ4TEST_SRCS})
 target_link_libraries(sj4test PRIVATE sj4core)
 
-#target_compile_definitions(sj4core PUBLIC SJ4_GLOBAL)
+if(SJ4_GLOBAL)
+	target_compile_definitions(sj4core PUBLIC SJ4_GLOBAL)
+endif()
 
 target_compile_definitions(sj4mkdic PRIVATE UTF8 ENGLISH)
diff --git a/README b/README
index 9e3a23f..0ae96ed 100644
--- a/README
+++ b/README
@@ -29,14 +29,21 @@
 	PC				Linux 6.6.87.2-microsoft-standard-WSL2 
 					Windows 11
 
+* Differences
+	 - Multiple contexts can be created in SJ4. SJ3's behavior of using
+	   global variables can be brought back with -DSJ3_GLOBAL.
+	 - Dictionary input is UTF-8 instead of EUC-JP, but output binary is
+	   still in EUC-JP. This allows SJ4 to use characters like emojis.
+	 - SJ4 is monolithic unlike SJ3, which is C/S.
+	 - SJ4 has Windows support.
+
 * Bug report
 	If some bugs are found, please send bug report(Japanese or English)
 	https://forgejo.nishi.boats/pyrite-dev/sj4
 	or send me email at nishi@nishi.boats.
 
 * Acknowledgements
-
-	I would like to thank to the people who worked on Sj3 originally,
+	I would like to thank to the people who worked on SJ3 originally,
 	including Sony Corporation.
 
                                                               June 20, 2026