diff --git a/tests/liberty/run-test.sh b/tests/liberty/run-test.sh
index 771bb69f7..ff5b20d74 100755
--- a/tests/liberty/run-test.sh
+++ b/tests/liberty/run-test.sh
@@ -8,3 +8,8 @@ for x in *.lib; do
 	../../yosys-filterlib -verilogsim $x > $x.verilogsim
 	diff $x.filtered $x.filtered.ok && diff $x.verilogsim $x.verilogsim.ok
 done
+
+for x in *.ys; do
+  echo "Running $x.."
+  ../../yosys -q -s $x -l ${x%.ys}.log
+done
diff --git a/tests/liberty/unit_delay.ys b/tests/liberty/unit_delay.ys
new file mode 100644
index 000000000..8dd409183
--- /dev/null
+++ b/tests/liberty/unit_delay.ys
@@ -0,0 +1,3 @@
+# Nothing gets imported: the file lacks timing data
+read_liberty -wb -unit_delay normal.lib
+select -assert-none =*/t:$specify*