diff --git a/crypto/objects/obj_xref.h b/crypto/objects/obj_xref.h
index cfd628a78..433c96bb4 100644
--- a/crypto/objects/obj_xref.h
+++ b/crypto/objects/obj_xref.h
@@ -53,9 +53,6 @@ static const nid_triple sigoid_srt[] =
 
 static const nid_triple * const sigoid_srt_xref[] =
 	{
-	&sigoid_srt[29],
-	&sigoid_srt[17],
-	&sigoid_srt[18],
 	&sigoid_srt[0],
 	&sigoid_srt[1],
 	&sigoid_srt[7],
diff --git a/crypto/objects/objxref.pl b/crypto/objects/objxref.pl
index 94b9bc133..833f4ab88 100644
--- a/crypto/objects/objxref.pl
+++ b/crypto/objects/objxref.pl
@@ -91,7 +91,10 @@ EOF
 
 foreach (@srt2)
 	{
-	my $x = $xref_tbl{$_}[2];
+	my ($p1, $p2, $x) = @{$xref_tbl{$_}};
+	# If digest or signature algorithm is "undef" then the algorithm
+	# needs special handling and is excluded from the cross reference table.
+	next if $p1 eq "undef" || $p2 eq "undef";
 	print "\t\&sigoid_srt\[$x\],\n";
 	}