diff --git a/include/cinatra/version.hpp b/include/cinatra/version.hpp
new file mode 100644
index 00000000..4ba2c29f
--- /dev/null
+++ b/include/cinatra/version.hpp
@@ -0,0 +1,8 @@
+#pragma once
+
+// Note: Update the version when release a new version.
+
+// CINATRA_VERSION % 100 is the sub-minor version
+// CINATRA_VERSION / 100 % 1000 is the minor version
+// CINATRA_VERSION / 100000 is the major version
+#define CINATRA_VERSION 901  // 0.9.1
\ No newline at end of file