diff --git a/scripts/docs-drift.pl b/scripts/docs-drift.pl
index 87a224c..14623ad 100755
--- a/scripts/docs-drift.pl
+++ b/scripts/docs-drift.pl
@@ -1,4 +1,7 @@
 #!/usr/bin/env perl
+# Copyright (c) 2026 Petr Balvín <opensource@petrbalvin.org> (https://petrbalvin.org)
+# SPDX-License-Identifier: MIT
+
 # docs-drift compares the toml-test suite counts the documentation names with
 # the run this repository produces now. A corpus change moves the counts, and
 # README.md and docs/ARCHITECTURE.md quote them; this is the check that keeps
@@ -6,26 +9,36 @@
 
 use v5.40;
 
-my $out = qx{toml-test test -decoder=bin/interpres-decode -encoder='bin/interpres-decode -encode' -toml=1.1 2>&1};
+my $out = qx{toml-test test -decoder=bin/interpres-decode -encoder='bin/interpres-decode --encode' -toml=1.1 2>&1};
 die "docs-drift: toml-test failed to run; build the adapter first (just build)\n"
     if !defined $out || $out =~ /not found|No such file/;
+# A red run is a failure to answer, not a drift: the counts it prints describe
+# a suite that did not pass, and sending the maintainer to correct counts that
+# are correct would be the wrong diagnosis.
+die "docs-drift: the toml-test run failed; fix the suite before comparing counts\n"
+    if $? != 0;
 
-my ($valid) = $out =~ /valid tests:\s+(\d+) passed/;
-my ($invalid) = $out =~ /invalid tests:\s+(\d+) passed/;
-die "docs-drift: could not read the suite counts from the toml-test output\n"
-    unless defined $valid && defined $invalid;
-print "docs-drift: the suite now stands at $valid valid and $invalid invalid cases\n";
+my %live;
+for my $kind (qw(valid invalid encoder)) {
+    my ($passed) = $out =~ /\b$kind tests:\s+(\d+) passed/;
+    die "docs-drift: could not read the $kind count from the toml-test output\n"
+        unless defined $passed;
+    my ($failed) = $out =~ /\b$kind tests:\s+\d+ passed, (\d+) failed/;
+    die "docs-drift: the $kind run has $failed failures; fix the suite first\n"
+        if defined $failed && $failed != 0;
+    $live{$kind} = $passed;
+}
+print "docs-drift: the suite now stands at $live{valid} valid, $live{invalid} invalid and $live{encoder} encoder cases\n";
 
 my $drift = 0;
 for my $file ('README.md', 'docs/ARCHITECTURE.md') {
     open(my $fh, '<', $file) or die "docs-drift: cannot read $file: $!\n";
     my $text = do { local $/; <$fh> };
     close($fh);
-    while ($text =~ /(\d+)\s+(valid|invalid)/g) {
+    while ($text =~ /(\d+)\s+(valid|invalid|encoder)/g) {
         my ($quoted, $kind) = ($1, $2);
-        my $live = $kind eq 'valid' ? $valid : $invalid;
-        if ($quoted != $live) {
-            print "docs-drift: $file quotes $quoted $kind cases, the suite says $live\n";
+        if ($quoted != $live{$kind}) {
+            print "docs-drift: $file quotes $quoted $kind cases, the suite says $live{$kind}\n";
             $drift = 1;
         }
     }