diff --git a/include/mx/base.h b/include/mx/base.h
index a4c12f3..bc71d22 100644
--- a/include/mx/base.h
+++ b/include/mx/base.h
@@ -9,4 +9,6 @@
 #define MX_IMPL
 #define MX_INLINE inline static
 
+typedef int32_t mx_len_t;
+
 #endif
\ No newline at end of file