diff --git a/src/Crypto/jitterentropy-base.c b/src/Crypto/jitterentropy-base.c
index c3856b41..c25589b0 100644
--- a/src/Crypto/jitterentropy-base.c
+++ b/src/Crypto/jitterentropy-base.c
@@ -53,7 +53,7 @@
 
 
 #ifdef TC_WINDOWS_DRIVER
-#define UINT64_MAX	0xffffffffffffffffU
+#define UINT64_MAX	 0xffffffffffffffffui64
 #else
 #include <stdint.h>
 #endif