diff --git a/ivtest/ivltests/module_instance_no_ports_fail.v b/ivtest/ivltests/module_instance_no_ports_fail.v
new file mode 100644
index 000000000..da2b5f639
--- /dev/null
+++ b/ivtest/ivltests/module_instance_no_ports_fail.v
@@ -0,0 +1,8 @@
+// Check that a scalar module instance requires port parentheses.
+
+module M;
+endmodule
+
+module test;
+  M m;
+endmodule
diff --git a/ivtest/ivltests/module_instance_no_ports_mixed_fail.v b/ivtest/ivltests/module_instance_no_ports_mixed_fail.v
new file mode 100644
index 000000000..c4c548856
--- /dev/null
+++ b/ivtest/ivltests/module_instance_no_ports_mixed_fail.v
@@ -0,0 +1,8 @@
+// Check that a mixed instance list cannot omit scalar port parentheses.
+
+module M;
+endmodule
+
+module test;
+  M first [1:0], middle, last();
+endmodule
diff --git a/ivtest/ivltests/module_no_port_mixed_instances.v b/ivtest/ivltests/module_no_port_mixed_instances.v
new file mode 100644
index 000000000..77173f70e
--- /dev/null
+++ b/ivtest/ivltests/module_no_port_mixed_instances.v
@@ -0,0 +1,17 @@
+// Check that an instance list can mix omitted and empty port lists.
+
+module M;
+  localparam VALUE = 1;
+endmodule
+
+module test;
+  M first [1:0], middle(), last [1:0];
+
+  initial begin
+    if (first[0].VALUE !== 1 || first[1].VALUE !== 1 ||
+        middle.VALUE !== 1 || last[0].VALUE !== 1 || last[1].VALUE !== 1)
+      $display("FAILED");
+    else
+      $display("PASSED");
+  end
+endmodule
diff --git a/ivtest/regress-vvp.list b/ivtest/regress-vvp.list
index 00de5ee70..8ceea6ff5 100644
--- a/ivtest/regress-vvp.list
+++ b/ivtest/regress-vvp.list
@@ -174,6 +174,9 @@ memsynth9			vvp_tests/memsynth9.json
 memsynth9-synth			vvp_tests/memsynth9-synth.json
 mix_reset			vvp_tests/mix_reset.json
 mix_reset-synth			vvp_tests/mix_reset-synth.json
+module_instance_no_ports_fail	vvp_tests/module_instance_no_ports_fail.json
+module_instance_no_ports_mixed_fail	vvp_tests/module_instance_no_ports_mixed_fail.json
+module_no_port_mixed_instances	vvp_tests/module_no_port_mixed_instances.json
 module_ordered_list1		vvp_tests/module_ordered_list1.json
 module_ordered_list2		vvp_tests/module_ordered_list2.json
 module_port_array1		vvp_tests/module_port_array1.json
diff --git a/ivtest/vvp_tests/module_instance_no_ports_fail.json b/ivtest/vvp_tests/module_instance_no_ports_fail.json
new file mode 100644
index 000000000..418bed903
--- /dev/null
+++ b/ivtest/vvp_tests/module_instance_no_ports_fail.json
@@ -0,0 +1,4 @@
+{
+    "type"   : "CE",
+    "source" : "module_instance_no_ports_fail.v"
+}
diff --git a/ivtest/vvp_tests/module_instance_no_ports_mixed_fail.json b/ivtest/vvp_tests/module_instance_no_ports_mixed_fail.json
new file mode 100644
index 000000000..48720e9a4
--- /dev/null
+++ b/ivtest/vvp_tests/module_instance_no_ports_mixed_fail.json
@@ -0,0 +1,4 @@
+{
+    "type"   : "CE",
+    "source" : "module_instance_no_ports_mixed_fail.v"
+}
diff --git a/ivtest/vvp_tests/module_no_port_mixed_instances.json b/ivtest/vvp_tests/module_no_port_mixed_instances.json
new file mode 100644
index 000000000..6851d60be
--- /dev/null
+++ b/ivtest/vvp_tests/module_no_port_mixed_instances.json
@@ -0,0 +1,4 @@
+{
+    "type"   : "normal",
+    "source" : "module_no_port_mixed_instances.v"
+}