diff --git a/src/bin/initdb/findtimezone.c b/src/bin/initdb/findtimezone.c
index 95958734ca..5a443131ee 100644
--- a/src/bin/initdb/findtimezone.c
+++ b/src/bin/initdb/findtimezone.c
@@ -99,15 +99,15 @@ pg_load_tz(const char *name)
 	 */
 	if (strcmp(name, "GMT") == 0)
 	{
-		if (tzparse(name, &tz.state, TRUE) != 0)
+		if (!tzparse(name, &tz.state, true))
 		{
 			/* This really, really should not happen ... */
 			return NULL;
 		}
 	}
-	else if (tzload(name, NULL, &tz.state, TRUE) != 0)
+	else if (tzload(name, NULL, &tz.state, true) != 0)
 	{
-		if (name[0] == ':' || tzparse(name, &tz.state, FALSE) != 0)
+		if (name[0] == ':' || !tzparse(name, &tz.state, false))
 		{
 			return NULL;		/* unknown timezone */
 		}
diff --git a/src/timezone/localtime.c b/src/timezone/localtime.c
index 23e022695f..985ad56da2 100644
--- a/src/timezone/localtime.c
+++ b/src/timezone/localtime.c
@@ -409,7 +409,7 @@ tzloadbody(char const * name, char *canonname, struct state * sp, bool doextend,
 		struct state *ts = &lsp->u.st;
 
 		up->buf[nread - 1] = '\0';
-		if (tzparse(&up->buf[1], ts, false) == 0
+		if (tzparse(&up->buf[1], ts, false)
 			&& ts->typecnt == 2)
 		{
 			/*
@@ -534,7 +534,7 @@ tzloadbody(char const * name, char *canonname, struct state * sp, bool doextend,
  * given name is stored there (the buffer must be > TZ_STRLEN_MAX bytes!).
  */
 int
-tzload(const char *name, char *canonname, struct state * sp, int doextend)
+tzload(const char *name, char *canonname, struct state * sp, bool doextend)
 {
 	union local_storage ls;
 
@@ -864,13 +864,10 @@ transtime(int year, const struct rule * rulep,
 /*
  * Given a POSIX section 8-style TZ string, fill in the rule tables as
  * appropriate.
- *
- * Returns 0 on success, -1 on failure.  (Note: tzcode has converted this
- * to a bool true-on-success convention, but we're holding the line in PG
- * for the moment, to avoid external API changes.)
+ * Returns true on success, false on failure.
  */
-int
-tzparse(const char *name, struct state * sp, int lastditch)
+bool
+tzparse(const char *name, struct state * sp, bool lastditch)
 {
 	const char *stdname;
 	const char *dstname = NULL;
@@ -908,7 +905,7 @@ tzparse(const char *name, struct state * sp, int lastditch)
 			stdname = name;
 			name = getqzname(name, '>');
 			if (*name != '>')
-				return -1;
+				return false;
 			stdlen = name - stdname;
 			name++;
 		}
@@ -918,13 +915,13 @@ tzparse(const char *name, struct state * sp, int lastditch)
 			stdlen = name - stdname;
 		}
 		if (*name == '\0')		/* we allow empty STD abbrev, unlike IANA */
-			return -1;
+			return false;
 		name = getoffset(name, &stdoffset);
 		if (name == NULL)
-			return -1;
+			return false;
 		charcnt = stdlen + 1;
 		if (sizeof sp->chars < charcnt)
-			return -1;
+			return false;
 		load_ok = tzload(TZDEFRULES, NULL, sp, false) == 0;
 	}
 	if (!load_ok)
@@ -936,7 +933,7 @@ tzparse(const char *name, struct state * sp, int lastditch)
 			dstname = ++name;
 			name = getqzname(name, '>');
 			if (*name != '>')
-				return -1;
+				return false;
 			dstlen = name - dstname;
 			name++;
 		}
@@ -947,15 +944,15 @@ tzparse(const char *name, struct state * sp, int lastditch)
 			dstlen = name - dstname;	/* length of DST zone name */
 		}
 		if (!dstlen)
-			return -1;
+			return false;
 		charcnt += dstlen + 1;
 		if (sizeof sp->chars < charcnt)
-			return -1;
+			return false;
 		if (*name != '\0' && *name != ',' && *name != ';')
 		{
 			name = getoffset(name, &dstoffset);
 			if (name == NULL)
-				return -1;
+				return false;
 		}
 		else
 			dstoffset = stdoffset - SECSPERHOUR;
@@ -972,13 +969,13 @@ tzparse(const char *name, struct state * sp, int lastditch)
 
 			++name;
 			if ((name = getrule(name, &start)) == NULL)
-				return -1;
+				return false;
 			if (*name++ != ',')
-				return -1;
+				return false;
 			if ((name = getrule(name, &end)) == NULL)
-				return -1;
+				return false;
 			if (*name != '\0')
-				return -1;
+				return false;
 			sp->typecnt = 2;	/* standard time and DST */
 
 			/*
@@ -1044,7 +1041,7 @@ tzparse(const char *name, struct state * sp, int lastditch)
 			int			j;
 
 			if (*name != '\0')
-				return -1;
+				return false;
 
 			/*
 			 * Initial values of theirstdoffset and theirdstoffset.
@@ -1148,7 +1145,7 @@ tzparse(const char *name, struct state * sp, int lastditch)
 		memcpy(cp, dstname, dstlen);
 		*(cp + dstlen) = '\0';
 	}
-	return 0;
+	return true;
 }
 
 static void
diff --git a/src/timezone/pgtz.c b/src/timezone/pgtz.c
index c28e6dbfad..4fa3d0da89 100644
--- a/src/timezone/pgtz.c
+++ b/src/timezone/pgtz.c
@@ -256,7 +256,7 @@ pg_tzset(const char *name)
 	 */
 	if (strcmp(uppername, "GMT") == 0)
 	{
-		if (tzparse(uppername, &tzstate, true) != 0)
+		if (!tzparse(uppername, &tzstate, true))
 		{
 			/* This really, really should not happen ... */
 			elog(ERROR, "could not initialize GMT time zone");
@@ -266,7 +266,7 @@ pg_tzset(const char *name)
 	}
 	else if (tzload(uppername, canonname, &tzstate, true) != 0)
 	{
-		if (uppername[0] == ':' || tzparse(uppername, &tzstate, false) != 0)
+		if (uppername[0] == ':' || !tzparse(uppername, &tzstate, false))
 		{
 			/* Unknown timezone. Fail our call instead of loading GMT! */
 			return NULL;
diff --git a/src/timezone/pgtz.h b/src/timezone/pgtz.h
index deee7464ed..2adec19838 100644
--- a/src/timezone/pgtz.h
+++ b/src/timezone/pgtz.h
@@ -69,7 +69,7 @@ extern int	pg_open_tzfile(const char *name, char *canonname);
 
 /* in localtime.c */
 extern int tzload(const char *name, char *canonname, struct state * sp,
-	   int doextend);
-extern int	tzparse(const char *name, struct state * sp, int lastditch);
+	   bool doextend);
+extern bool tzparse(const char *name, struct state * sp, bool lastditch);
 
 #endif   /* _PGTZ_H */