1 files changed, 2 insertions, 2 deletions
diff --git a/lib/Net/IMAP/Sync.pm b/lib/Net/IMAP/Sync.pm
index 26303a6..bf56519 100644
--- a/lib/Net/IMAP/Sync.pm
+++ b/lib/Net/IMAP/Sync.pm
@@ -657,12 +657,12 @@ sub append($$@) {
     my @uids;
     foreach (split /,/, $uidset) {
         if (/\A([0-9]+)\z/) {
-            $UIDNEXT = $1 + 1 if $UIDNEXT <= $1;
+            $UIDNEXT = $1 + 1 if defined $UIDNEXT and $UIDNEXT <= $1;
             push @uids, $1;
         } elsif (/\A([0-9]+):([0-9]+)\z/) {
             my ($min, $max) = $1 <= $2 ? ($1,$2) : ($2,$1);
             push @uids, ($min .. $max);
-            $UIDNEXT = $max + 1 if $UIDNEXT <= $max;
+            $UIDNEXT = $max + 1 if defined $UIDNEXT and $UIDNEXT <= $max;
         } else {
             $self->panic($_);
         }