diff --git a/src/test/compile-fail/occurs-check-3.rs b/src/test/compile-fail/occurs-check-3.rs
new file mode 100644
index 000000000000..f0439b87aed8
--- /dev/null
+++ b/src/test/compile-fail/occurs-check-3.rs
@@ -0,0 +1,4 @@
+// error-pattern:mismatched types
+// From Issue #778
+tag clam[T] { a(T); }
+fn main() { let c = a(c); alt c { a[int](_) { } } }