diff --git a/include/ruby/io/buffer.h b/include/ruby/io/buffer.h
index 907fec20bb..726c26d157 100644
--- a/include/ruby/io/buffer.h
+++ b/include/ruby/io/buffer.h
@@ -51,13 +51,13 @@ enum rb_io_buffer_endian {
     RB_IO_BUFFER_LITTLE_ENDIAN = 4,
     RB_IO_BUFFER_BIG_ENDIAN = 8,
 
-#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
+#if defined(__BYTE_ORDER__) && __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
     RB_IO_BUFFER_HOST_ENDIAN = RB_IO_BUFFER_LITTLE_ENDIAN,
-#elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
+#elif defined(__BYTE_ORDER__) && __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
     RB_IO_BUFFER_HOST_ENDIAN = RB_IO_BUFFER_BIG_ENDIAN,
-#elif REG_DWORD == REG_DWORD_LITTLE_ENDIAN
+#elif defined(REG_DWORD) && REG_DWORD == REG_DWORD_LITTLE_ENDIAN
     RB_IO_BUFFER_HOST_ENDIAN = RB_IO_BUFFER_LITTLE_ENDIAN,
-#elif REG_DWORD == REG_DWORD_BIG_ENDIAN
+#elif defined(REG_DWORD) && REG_DWORD == REG_DWORD_BIG_ENDIAN
     RB_IO_BUFFER_HOST_ENDIAN = RB_IO_BUFFER_BIG_ENDIAN,
 #endif
 
diff --git a/version.h b/version.h
index 38ddc3ec67..8915a06a9e 100644
--- a/version.h
+++ b/version.h
@@ -11,7 +11,7 @@
 # define RUBY_VERSION_MINOR RUBY_API_VERSION_MINOR
 #define RUBY_VERSION_TEENY 5
 #define RUBY_RELEASE_DATE RUBY_RELEASE_YEAR_STR"-"RUBY_RELEASE_MONTH_STR"-"RUBY_RELEASE_DAY_STR
-#define RUBY_PATCHLEVEL 256
+#define RUBY_PATCHLEVEL 257
 
 #define RUBY_RELEASE_YEAR 2024
 #define RUBY_RELEASE_MONTH 5