diff --git a/zdump.c b/zdump.c
index 16e73ae..42b7027 100644
--- a/zdump.c
+++ b/zdump.c
@@ -660,6 +660,15 @@ yeartot(intmax_t y)
 	return t;
 }
 
+
+static void
+printtm(char const *name, struct tm const *tm, char const *abbr)
+{
+  printf(" %s={%d-%.3dT%.2d:%.2d:%.2d dst=%d abbr='%s'}",
+	 name, tm->tm_year + 1900, tm->tm_yday + 1,
+	 tm->tm_hour, tm->tm_min, tm->tm_sec, tm->tm_isdst, abbr);
+}
+
 /* Search for a discontinuity in timezone TZ with name NAME, in the
    timestamps ranging from LOT (with broken-down time LOTMP if
    nonnull) through HIT.  LOT and HIT disagree about some aspect of
@@ -693,9 +702,50 @@ hunt(timezone_t tz, char *name, time_t lot, struct tm *lotmp, time_t hit,
 			    - ((lot % 2 + hit % 2) < 0)
 			    + ((lot % 2 + hit % 2) == 2)
 			    + hit / 2);
+
+		time_t diff = hit - lot, altt;
+		if ((diff < 2) != (t == lot)) {
+		  printf("TRACING: bad break - lot="); printf(tformat(), lot);
+		  printf(" t="); printf(tformat(), t);
+		  printf(" hit="); printf(tformat(), hit);
+		  printf(" diff="); printf(tformat(), diff);
+		  printf("\n");
+		}
+
 		if (t == lot)
 			break;
+
+		altt = lot;
+		altt += diff / 2;
+		if (altt <= lot)
+		  ++altt;
+		else if (altt >= hit)
+		  --altt;
+		if (t != altt) {
+		  printf("TRACING: bad t - lot="); printf(tformat(), lot);
+		  printf(" t="); printf(tformat(), t);
+		  printf(" hit="); printf(tformat(), hit);
+		  printf(" altt="); printf(tformat(), altt);
+		  printf("\n");
+		}
+
 		tm_ok = my_localtime_rz(tz, &t, &tm) != NULL;
+
+		printf("TRACING: lotm_ok=%d tm_ok=%d only_ok=%d lot=",
+		       lotm_ok, tm_ok, only_ok);
+		printf(tformat(), lot);
+		printf(" t=");
+		printf(tformat(), t);
+		if (lotm_ok == tm_ok && !only_ok) {
+		  printtm("tm", &tm, abbr(&tm));
+		  printtm("lotm", &lotm, ab);
+		  printf(" delta=%jd t-lot=", delta(&tm, &lotm));
+		  printf(tformat(), t - lot);
+		}
+		printf(" hit=");
+		printf(tformat(), hit);
+		printf("\n");
+
 		if (lotm_ok == tm_ok
 		    && (only_ok
 			|| (lotm_ok && tm.tm_isdst == lotm.tm_isdst