diff --git a/include/jemalloc/internal/nstime.h b/include/jemalloc/internal/nstime.h
index bd04f04b..dcb4b47f 100644
--- a/include/jemalloc/internal/nstime.h
+++ b/include/jemalloc/internal/nstime.h
@@ -7,7 +7,7 @@
 typedef struct nstime_s nstime_t;
 
 /* Maximum supported number of seconds (~584 years). */
-#define	NSTIME_SEC_MAX	18446744072
+#define	NSTIME_SEC_MAX	KQU(18446744072)
 
 #endif /* JEMALLOC_H_TYPES */
 /******************************************************************************/
diff --git a/src/arena.c b/src/arena.c
index 965c0fe2..f436959e 100644
--- a/src/arena.c
+++ b/src/arena.c
@@ -1352,7 +1352,11 @@ static bool
 arena_decay_time_valid(ssize_t decay_time)
 {
 
-	return (decay_time >= -1 && decay_time <= NSTIME_SEC_MAX);
+	if (decay_time < -1)
+		return (false);
+	if (decay_time == -1 || (uint64_t)decay_time <= NSTIME_SEC_MAX)
+		return (true);
+	return (false);
 }
 
 ssize_t