diff -ru a/src/tool_msgs.c b/src/tool_msgs.c
--- a/src/tool_msgs.c	2019-01-03 20:29:22.836975839 +0000
+++ b/src/tool_msgs.c	2019-01-03 22:00:12.262355341 +0000
@@ -67,7 +67,7 @@
         (void)fwrite(ptr, cut + 1, 1, config->errors);
         fputs("\n", config->errors);
         ptr += cut + 1; /* skip the space too */
-        len -= cut;
+        len -= cut + 1;
       }
       else {
         fputs(ptr, config->errors);