diff --git a/src/lib/common/xundump.c b/src/lib/common/xundump.c
index 1301d7de..e361c8bc 100644
--- a/src/lib/common/xundump.c
+++ b/src/lib/common/xundump.c
@@ -82,6 +82,7 @@ static struct castr **fldca;	/* Map field number to selector */
 static int *fldidx;		/* Map field number to index */
 static int *caflds;		/* Map selector number to #fields seen */
 static int *cafldspp;		/* ditto, in previous parts */
+static int may_omit_id;		/* Okay to omit IDs? */
 static int may_trunc;		/* Okay to truncate? */
 
 static int gripe(char *, ...) ATTRIBUTE((format (printf, 1, 2)));
@@ -224,6 +225,8 @@ tbl_skip_to_obj(int id)
     int max_id, exp_id;
 
     if (partno == 0) {
+	if (!may_omit_id && id != cur_id + 1)
+	    return gripe("Expected %d in field %d", cur_id + 1, 1);
 	if (id <= cur_id)
 	    return gripe("Field %d must be > %d", 1, cur_id);
 	max_id = ef_id_limit(cur_type);
@@ -1075,13 +1078,14 @@ xundump(FILE *fp, char *file, int *plno, int expected_table)
 	return -1;
 
     nca = nf = 0;
+    may_omit_id = 1;
     may_trunc = empfile[type].nent < 0;
     for (i = 0; ca[i].ca_name; i++) {
 	nca++;
 	if (!(ca[i].ca_flags & NSC_EXTRA)) {
 	    nf += MAX(1, ca[i].ca_type != NSC_STRINGY ? ca[i].ca_len : 0);
 	    if (ca[i].ca_flags & NSC_CONST)
-		may_trunc = 0;
+		may_omit_id = may_trunc = 0;
 	}
     }
     fldca = malloc(nf * sizeof(*fldca));