diff --git a/test/aggregate-results.sh b/test/aggregate-results.sh
index 75400e6e..6845fcf0 100755
--- a/test/aggregate-results.sh
+++ b/test/aggregate-results.sh
@@ -8,9 +8,16 @@ failed=0
 broken=0
 total=0
 all_skipped=0
+rep_failed=0
 
 for file
 do
+	if [ ! -f "$file" ]; then
+		echo "'$file' does not exist!"
+		rep_failed=$((rep_failed + 1))
+		continue
+	fi
+	has_total=0
 	while read type value
 	do
 		case $type in
@@ -24,18 +31,23 @@ do
 			broken=$((broken + value)) ;;
 		total)
 			total=$((total + value))
+			has_total=1
 			if [ "$value" -eq 0 ]; then
 				all_skipped=$((all_skipped + 1))
 			fi
 		esac
 	done <"$file"
+	if [ "$has_total" -eq 0 ]; then
+		echo "'$file' lacks 'total ...'; results may be inconsistent."
+		failed=$((failed + 1))
+	fi
 done
 
 pluralize_s () { [ "$1" -eq 1 ] && s='' || s='s'; }
 
 echo "Notmuch test suite complete."
 
-if [ "$fixed" -eq 0 ] && [ "$failed" -eq 0 ]; then
+if [ "$fixed" -eq 0 ] && [ "$failed" -eq 0 ] && [ "$rep_failed" -eq 0 ]; then
 	pluralize_s "$total"
 	printf "All $total test$s "
 	if [ "$broken" -eq 0 ]; then
@@ -70,10 +82,16 @@ if [ "$all_skipped" -ne 0 ]; then
 	echo "All tests in $all_skipped file$s skipped."
 fi
 
+if [ "$rep_failed" -ne 0 ]; then
+	pluralize_s "$rep_failed"
+	echo "$rep_failed test$s failed to report results."
+fi
+
 # Note that we currently do not consider skipped tests as failing the
 # build.
 
-if [ "$success" -gt 0 ] && [ "$fixed" -eq 0 ] && [ "$failed" -eq 0 ]
+if [ "$success" -gt 0 ] && [ "$fixed" -eq 0 ] &&
+	[ "$failed" -eq 0 ] && [ "$rep_failed" -eq 0 ]
 then
 	exit 0
 else
diff --git a/test/notmuch-test b/test/notmuch-test
index cbd33f93..ce142f7c 100755
--- a/test/notmuch-test
+++ b/test/notmuch-test
@@ -18,12 +18,14 @@ fi
 # Ensure NOTMUCH_SRCDIR and NOTMUCH_BUILDDIR are set.
 . $(dirname "$0")/export-dirs.sh || exit 1
 
+set -eu
+
 TESTS=
-for test in $NOTMUCH_TESTS; do
+for test in ${NOTMUCH_TESTS-}; do
     TESTS="$TESTS $NOTMUCH_SRCDIR/test/$test"
 done
 
-if [[ -z "$TESTS" ]]; then
+if [ -z "$TESTS" ]; then
     TESTS="$NOTMUCH_SRCDIR/test/T[0-9][0-9][0-9]-*.sh"
 fi
 
@@ -44,43 +46,46 @@ else
     TEST_TIMEOUT_CMD=""
 fi
 
-trap 'e=$?; kill $!; exit $e' HUP INT TERM
-
 META_FAILURE=
+RES=0
 # Run the tests
-if test -z "$NOTMUCH_TEST_SERIALIZE" && command -v parallel >/dev/null ; then
+if test -z "${NOTMUCH_TEST_SERIALIZE-}" && command -v parallel >/dev/null ; then
     test -t 1 && export COLORS_WITHOUT_TTY=t || :
     if parallel --version 2>&1 | grep -q GNU ; then
         echo "INFO: running tests with GNU parallel"
-        printf '%s\n' $TESTS | $TEST_TIMEOUT_CMD parallel
+        printf '%s\n' $TESTS | $TEST_TIMEOUT_CMD parallel || RES=$?
     else
         echo "INFO: running tests with moreutils parallel"
-        $TEST_TIMEOUT_CMD parallel -- $TESTS
+        $TEST_TIMEOUT_CMD parallel -- $TESTS || RES=$?
     fi
-    RES=$?
-    if [[ $RES != 0 ]]; then
+    if [ $RES != 0 ]; then
         META_FAILURE="parallel test suite returned error code $RES"
     fi
 else
+    trap 'e=$?; trap - 0; kill ${!-}; exit $e' 0 HUP INT TERM
     for test in $TESTS; do
         $TEST_TIMEOUT_CMD $test "$@" &
-        wait $!
-        # If the test failed without producing results, then it aborted,
-        # so we should abort, too.
-        RES=$?
-        testname=$(basename $test .sh)
-        if [[ $RES != 0 && ! -e "$NOTMUCH_BUILDDIR/test/test-results/$testname" ]]; then
-            META_FAILURE="Aborting on $testname (returned $RES)"
-            break
-        fi
+        wait $! && ev=0 || ev=$?
+        test $ev = 0 || RES=$ev
     done
+    trap - 0 HUP INT TERM
+    if [ $RES != 0 ]; then
+        META_FAILURE="some tests failed; first failed returned error code $RES"
+    fi
 fi
-trap - HUP INT TERM
 
 # Report results
+RESULT_FILES=
+for file in $TESTS
+do
+    file=${file##*/} # drop leading path components
+    file=${file%.sh} # drop trailing '.sh'
+    RESULT_FILES="$RESULT_FILES $NOTMUCH_BUILDDIR/test/test-results/$file"
+done
+
 echo
-$NOTMUCH_SRCDIR/test/aggregate-results.sh $NOTMUCH_BUILDDIR/test/test-results/*
-ev=$?
+$NOTMUCH_SRCDIR/test/aggregate-results.sh $RESULT_FILES && ev=0 || ev=$?
+
 if [ -n "$META_FAILURE" ]; then
     printf 'ERROR: %s\n' "$META_FAILURE"
     if [ $ev = 0 ]; then
diff --git a/test/test-lib.sh b/test/test-lib.sh
index 0bca76df..23f7c8f8 100644
--- a/test/test-lib.sh
+++ b/test/test-lib.sh
@@ -858,15 +858,16 @@ test_when_finished () {
 test_done () {
 	GIT_EXIT_OK=t
 	test_results_dir="$TEST_DIRECTORY/test-results"
-	mkdir -p "$test_results_dir"
+	test -d "$test_results_dir" || mkdir "$test_results_dir"
 	test_results_path="$test_results_dir/$this_test"
 
-	echo "total $test_count" >> $test_results_path
-	echo "success $test_success" >> $test_results_path
-	echo "fixed $test_fixed" >> $test_results_path
-	echo "broken $test_broken" >> $test_results_path
-	echo "failed $test_failure" >> $test_results_path
-	echo "" >> $test_results_path
+	printf %s\\n \
+		"success $test_success" \
+		"fixed $test_fixed" \
+		"broken $test_broken" \
+		"failed $test_failure" \
+		"total $test_count" \
+	    > $test_results_path
 
 	[ -n "$EMACS_SERVER" ] && test_emacs '(kill-emacs)'