diff --git a/lib/int_sqrt.c b/lib/int_sqrt.c
index a5d2cdc..fd355a9 100644
--- a/lib/int_sqrt.c
+++ b/lib/int_sqrt.c
@@ -15,7 +15,7 @@
 	op = x;
 	res = 0;
 
-	one = 1 << 30;
+	one = 1UL << (BITS_PER_LONG - 2);
 	while (one > op)
 		one >>= 2;