diff --git a/src/bin/pg_dump/pg_backup_archiver.c b/src/bin/pg_dump/pg_backup_archiver.c
index 8ea40ea7b76b8bea20f253d597899c34b004b85c..2b36e45533586589ed3dac8cad57054fffbb764f 100644
--- a/src/bin/pg_dump/pg_backup_archiver.c
+++ b/src/bin/pg_dump/pg_backup_archiver.c
@@ -3347,9 +3347,8 @@ checkSeek(FILE *fp)
 #endif
 
 	/* Check that ftello works on this file */
-	errno = 0;
 	tpos = ftello(fp);
-	if (errno)
+	if (tpos < 0)
 		return false;
 
 	/*
diff --git a/src/bin/pg_dump/pg_backup_tar.c b/src/bin/pg_dump/pg_backup_tar.c
index 06005ae8682a5cb55076b117603b7dd8a572e83b..3bdbf868189aacada76f5a842825c51c83f8b932 100644
--- a/src/bin/pg_dump/pg_backup_tar.c
+++ b/src/bin/pg_dump/pg_backup_tar.c
@@ -1068,6 +1068,9 @@ _tarAddFile(ArchiveHandle *AH, TAR_MEMBER *th)
 	 */
 	fseeko(tmp, 0, SEEK_END);
 	th->fileLen = ftello(tmp);
+	if (th->fileLen < 0)
+		exit_horribly(modulename, "could not determine seek position in file: %s\n",
+					  strerror(errno));
 	fseeko(tmp, 0, SEEK_SET);
 
 	/*
@@ -1212,20 +1215,6 @@ _tarGetHeader(ArchiveHandle *AH, TAR_MEMBER *th)
 
 	while (!gotBlock)
 	{
-#if 0
-		if (ftello(ctx->tarFH) != ctx->tarFHpos)
-		{
-			char		buf1[100],
-						buf2[100];
-
-			snprintf(buf1, sizeof(buf1), INT64_FORMAT, (int64) ftello(ctx->tarFH));
-			snprintf(buf2, sizeof(buf2), INT64_FORMAT, (int64) ftello(ctx->tarFHpos));
-			exit_horribly(modulename,
-			  "mismatch in actual vs. predicted file position (%s vs. %s)\n",
-						  buf1, buf2);
-		}
-#endif
-
 		/* Save the pos for reporting purposes */
 		hPos = ctx->tarFHpos;