diff --git a/libzfs.pyx b/libzfs.pyx
index 363ebe8..592f56f 100644
--- a/libzfs.pyx
+++ b/libzfs.pyx
@@ -2714,7 +2714,7 @@ cdef class ZPoolScrub(object):
             total = self.bytes_to_scan - self.stats.pss_skipped
             issued = self.bytes_issued
             elapsed = ((int(time.time()) - self.stats.pss_pass_start) - self.stats.pss_pass_scrub_spent_paused) or 1
-            pass_issued = self.stats.pss_pass_issued
+            pass_issued = self.stats.pss_pass_issued or 1
             issue_rate = pass_issued / elapsed
             return int((total - issued) / issue_rate)