diff --git a/src/lib/libc/contrib/tzcode/stdtime/localtime.c b/src/lib/libc/contrib/tzcode/stdtime/localtime.c
index 3c66924..05c01ae 100644
--- src/lib/libc/contrib/tzcode/stdtime/localtime.c
+++ src/lib/libc/contrib/tzcode/stdtime/localtime.c
@@ -1935,6 +1935,10 @@ time2sub(struct tm *const tmp,
 			lo *= 2;
 		hi = -(lo + 1);
 	}
+
+	lo = TIME_T_MIN;
+	hi = TIME_T_MAX;
+
 	for ( ; ; ) {
 		t = lo / 2 + hi / 2;
 		if (t < lo)
diff --git a/src/lib/libc/contrib/tzcode/stdtime/private.h b/src/lib/libc/contrib/tzcode/stdtime/private.h
index 354a78b..8300ba0 100644
--- src/lib/libc/contrib/tzcode/stdtime/private.h
+++ src/lib/libc/contrib/tzcode/stdtime/private.h
@@ -251,6 +251,24 @@ const char *	scheck(const char * string, const char * format);
 	1 + TYPE_SIGNED(type))
 #endif /* !defined INT_STRLEN_MAXIMUM */
 
+#define TWOS_COMPLEMENT(t) ((t) ~ (t) 0 < 0)
+
+/* Max and min values of the integer type T, of which only the bottom
+   B bits are used, and where the highest-order used bit is considered
+   to be a sign bit if T is signed.  */
+#define MAXVAL(t, b) \
+  ((t) (((t) 1 << ((b) - 1 - TYPE_SIGNED(t))) \
+  - 1 + ((t) 1 << ((b) - 1 - TYPE_SIGNED(t)))))
+#define MINVAL(t, b) \
+  ((t) (TYPE_SIGNED(t) ? - TWOS_COMPLEMENT(t) - MAXVAL(t, b) : 0))
+
+/* The extreme time values, assuming no padding.  */
+#define TIME_T_MIN_NO_PADDING MINVAL(time_t, TYPE_BIT(time_t))
+#define TIME_T_MAX_NO_PADDING MAXVAL(time_t, TYPE_BIT(time_t))
+
+# define TIME_T_MIN TIME_T_MIN_NO_PADDING
+# define TIME_T_MAX TIME_T_MAX_NO_PADDING
+
 /*
 ** INITIALIZE(x)
 */