diff --git a/git.spec b/git.spec
index cc7f53c..4c7d9bf 100644
--- a/git.spec
+++ b/git.spec
@@ -257,6 +257,7 @@ BuildRequires:  subversion-perl
 BuildRequires:  tar
 BuildRequires:  time
 BuildRequires:  zip
+BuildRequires:  zstd
 %endif
 # endif with tests
 
@@ -864,7 +865,7 @@ export GIT_TEST_SVN_HTTPD=true
 
 # Create tmpdir for test output and update GIT_TEST_OPTS
 # Also update GIT-BUILD-OPTIONS to keep make from any needless rebuilding
-testdir=$(mktemp -d -p /tmp git-t.XXXX)
+export testdir=$(mktemp -d -p /tmp git-t.XXXX)
 sed -i "s@^GIT_TEST_OPTS = .*@& --root=$testdir@" config.mak
 touch -r GIT-BUILD-OPTIONS ts
 sed -i "s@\(GIT_TEST_OPTS='.*\)'@\1 --root=$testdir'@" GIT-BUILD-OPTIONS
diff --git a/print-failed-test-output b/print-failed-test-output
index d0d63aa..4e65662 100644
--- a/print-failed-test-output
+++ b/print-failed-test-output
@@ -10,4 +10,17 @@ for exit_file in t/test-results/*.exit; do
     printf '\n%s\n%s\n%s\n' "$sep" "$out_file" "$sep"
     cat "$out_file"
 done
+
+# tar up test-results & $testdir, then print base64 encoded output
+#
+# copy $testdir contents to test-results to avoid absolute paths with tar
+cp -a $testdir/* t/test-results/
+begin='-----BEGIN BASE64 MESSAGE-----'
+end='-----END BASE64 MESSAGE-----'
+printf '\n%s\n' 'test-results and trash directory output follows; decode via:'
+printf '%s\n' "sed -n '/^${begin}$/,/^${end}$/{/^${begin}$/!{/^${end}$/!p}}' build.log | base64 -d >output.tar.zst"
+printf '%s\n' "$begin"
+tar -C t -cf - test-results/ | zstdmt -17 | base64
+printf '%s\n' "$end"
+
 exit 1