diff --git a/src/system/SYSTEM.h b/src/system/SYSTEM.h
index 420ca1cd..34b69a8a 100644
--- a/src/system/SYSTEM.h
+++ b/src/system/SYSTEM.h
@@ -60,7 +60,7 @@ typedef unsigned char U_SHORTINT;
 #if (__SIZEOF_POINTER__ == 8) || defined(LARGE) || defined(_WIN64)
   typedef int                INTEGER;   // INTEGER is 32 bit.
   typedef long long          LONGINT;   // LONGINT is 64 bit. (long long is always 64 bits, while long can be 32 bits e.g. under MSC/MingW)
-  typedef int                U_INTEGER;
+  typedef unsigned int       U_INTEGER;
   typedef unsigned long long U_LONGINT;
 #else
   typedef short int          INTEGER;   // INTEGER is 16 bit.