diff --git a/a/test.tf b/a/test.tf
new file mode 100644
index 0000000..a9c3985
--- /dev/null
+++ b/a/test.tf
@@ -0,0 +1 @@
+# no outputs
diff --git a/b/b.tf b/b/b.tf
new file mode 100644
index 0000000..91084f7
--- /dev/null
+++ b/b/b.tf
@@ -0,0 +1 @@
+variable "foo" {}
diff --git a/test.tf b/test.tf
new file mode 100644
index 0000000..c1c6882
--- /dev/null
+++ b/test.tf
@@ -0,0 +1,9 @@
+module "a" {
+    source = "a"
+    # this module has no outputs
+}
+
+module "b" {
+    source = "b"
+    foo = "${module.a.this_output_does_not_exist}"
+}