1 files changed, 5 insertions, 3 deletions
diff --git a/util/cutils.c b/util/cutils.c
index fd591cadf0..77acadc70a 100644
--- a/util/cutils.c
+++ b/util/cutils.c
@@ -239,10 +239,12 @@ static int do_strtosz(const char *nptr, const char **end,
         goto out;
     }
     /*
-     * Values >= 0xfffffffffffffc00 overflow uint64_t after their trip
-     * through double (53 bits of precision).
+     * Values near UINT64_MAX overflow to 2**64 when converting to double
+     * precision.  Compare against the maximum representable double precision
+     * value below 2**64, computed as "the next value after 2**64 (0x1p64) in
+     * the direction of 0".
      */
-    if ((val * mul >= 0xfffffffffffffc00) || val < 0) {
+    if ((val * mul > nextafter(0x1p64, 0)) || val < 0) {
         retval = -ERANGE;
         goto out;
     }