diff -up at-3.1.13/at.c.fclose at-3.1.13/at.c

--- at-3.1.13/at.c.fclose	2016-04-20 17:15:00.584327893 +0200

+++ at-3.1.13/at.c	2016-04-20 17:15:50.453609665 +0200

@@ -209,7 +209,11 @@ nextjob()

     jobno = (1 + jobno) % 0xfffff;	/* 2^20 jobs enough? */

     fprintf(fid, "%05lx\n", jobno);

-    fclose(fid);

+    if (ferror(fid))

+	jobno = EOF;

+

+    if (fclose(fid) != 0)

+	jobno = EOF;

     return jobno;

 }

@@ -498,7 +502,8 @@ writefile(time_t runtimer, char queue)

     if (ferror(stdin))

 	panic("Input error");

-    fclose(fp);

+    if (fclose(fp) != 0)

+	panic("Output error");

     /* Set the x bit so that we're ready to start executing

      */