diff --git a/mdeliver.c b/mdeliver.c
index 580219f..1a32af4 100644
--- a/mdeliver.c
+++ b/mdeliver.c
@@ -63,8 +63,7 @@ deliver(FILE *infile)
 			ssize_t rd = getdelim(&line, &linelen, '\n', infile);
 			if (rd == -1) {
 				if (errno == 0)
-					// invalid mbox file
-					errno = EINVAL;
+					errno = EINVAL;  // invalid mbox file
 				return -1;
 			}