diff --git a/compress42.c b/compress42.c
index 4d33342..495bdf3 100644
--- a/compress42.c
+++ b/compress42.c
@@ -1373,7 +1373,7 @@ compress(fdin, fdout)
REG11 int boff;
REG12 int n_bits;
REG13 int ratio;
- REG14 long checkpoint;
+ REG14 unsigned long long checkpoint;
REG15 code_int extcode;
union
{