diff --git a/src/pch.c b/src/pch.c
index 94a0ac1..3ba5394 100644
--- a/src/pch.c
+++ b/src/pch.c
@@ -2276,7 +2276,7 @@ pfetch (lin line)
 bool
 pch_write_line (lin line, FILE *file)
 {
-  bool after_newline = p_line[line][p_len[line] - 1] == '\n';
+  bool after_newline = (p_len[line] > 0) && (p_line[line][p_len[line] - 1] == '\n');
   if (! fwrite (p_line[line], sizeof (*p_line[line]), p_len[line], file))
     write_fatal ();
   return after_newline;