diff --git a/luna/src/Utf8.cpp b/luna/src/Utf8.cpp
index 4445c355..0e543381 100644
--- a/luna/src/Utf8.cpp
+++ b/luna/src/Utf8.cpp
@@ -1,6 +1,8 @@
 #include <luna/CString.h>
 #include <luna/Utf8.h>
 
+static_assert(__WCHAR_MAX__ > 0x10ffff);
+
 static Result<usize> utf8_char_length(char c)
 {
     if ((c & 0b11111000) == 0b11110000) return 4;