diff --git a/CryptoPkg/Library/Include/CrtLibSupport.h b/CryptoPkg/Library/Include/CrtLibSupport.h
index c09a9fabc7..613d418493 100644
--- a/CryptoPkg/Library/Include/CrtLibSupport.h
+++ b/CryptoPkg/Library/Include/CrtLibSupport.h
@@ -475,6 +475,10 @@ strpbrk (
 #define UINT64_MAX  0xFFFFFFFFFFFFFFFFUL
 #endif
 
+#ifndef ULLONG_MAX
+#define ULLONG_MAX  0xFFFFFFFFFFFFFFFFUL
+#endif
+
 #undef UINTPTR_MAX
 #if (UINT_MAX > 0xFFFFFFFFUL)
 #define UINTPTR_MAX  0xFFFFFFFFFFFFFFFFUL