diff --git a/src/bin/pg_upgrade/controldata.c b/src/bin/pg_upgrade/controldata.c
index fd772ba4f38..8c69329805b 100644
--- a/src/bin/pg_upgrade/controldata.c
+++ b/src/bin/pg_upgrade/controldata.c
@@ -352,7 +352,7 @@ get_control_data(ClusterInfo *cluster)
 				pg_fatal("%d: controldata retrieval problem", __LINE__);
 
 			p++;				/* remove ':' char */
-			cluster->controldata.chkpnt_nxtmxoff = str2uint(p);
+			cluster->controldata.chkpnt_nxtmxoff = str2uint64(p);
 			got_mxoff = true;
 		}
 		else if ((p = strstr(bufin, "First log segment after reset:")) != NULL)
diff --git a/src/bin/pg_upgrade/pg_upgrade.h b/src/bin/pg_upgrade/pg_upgrade.h
index ccd1ac0d013..92607daace5 100644
--- a/src/bin/pg_upgrade/pg_upgrade.h
+++ b/src/bin/pg_upgrade/pg_upgrade.h
@@ -496,6 +496,7 @@ void		cleanup_output_dirs(void);
 void		prep_status(const char *fmt, ...) pg_attribute_printf(1, 2);
 void		prep_status_progress(const char *fmt, ...) pg_attribute_printf(1, 2);
 unsigned int str2uint(const char *str);
+uint64		str2uint64(const char *str);
 
 
 /* version.c */
diff --git a/src/bin/pg_upgrade/util.c b/src/bin/pg_upgrade/util.c
index 08d6385b512..e7d7ab56445 100644
--- a/src/bin/pg_upgrade/util.c
+++ b/src/bin/pg_upgrade/util.c
@@ -353,3 +353,14 @@ str2uint(const char *str)
 {
 	return strtoul(str, NULL, 10);
 }
+
+/*
+ *	str2uint64()
+ *
+ *	convert string to uint64
+ */
+uint64
+str2uint64(const char *str)
+{
+	return strtou64(str, NULL, 10);
+}