diff --git a/LOG b/LOG
index 7bec4b119f..6af9311a2b 100644
--- a/LOG
+++ b/LOG
@@ -1025,3 +1025,4 @@
   where the cp register copy in the thread context could be changed
   in the callable prep before S_call_help gets it
     cpnanopass.ss, x86_64.ss, x86.ss, foreign2.c, foreign.ms
+- initialize all fields of seginfo to avoid undefined values
diff --git a/c/segment.c b/c/segment.c
index b578889658..28ac765165 100644
--- a/c/segment.c
+++ b/c/segment.c
@@ -228,7 +228,9 @@ static void initialize_seginfo(seginfo *si, ISPC s, IGEN g) {
 
   si->space = s;
   si->generation = g;
+  si->sorted = 0;
   si->min_dirty_byte = 0xff;
+  si->trigger_ephemerons = NULL;
   for (d = 0; d < cards_per_segment; d += sizeof(ptr)) {
     iptr *dp = (iptr *)(si->dirty_bytes + d);
     /* fill sizeof(iptr) bytes at a time with 0xff */