diff --git a/Userland/Libraries/LibC/limits.h b/Userland/Libraries/LibC/limits.h
index 69130b67a5..bfb7fc23f0 100644
--- a/Userland/Libraries/LibC/limits.h
+++ b/Userland/Libraries/LibC/limits.h
@@ -52,6 +52,7 @@
 #define LLONG_MIN LONG_LONG_MIN
 
 #define ULONG_LONG_MAX 18446744073709551615ULL
+#define ULLONG_MAX ULONG_LONG_MAX
 
 #define CHAR_MIN SCHAR_MIN
 #define CHAR_MAX SCHAR_MAX