diff --git a/src/comp/middle/trans_alt.rs b/src/comp/middle/trans_alt.rs
index 2410cd2ea47..066f969ba60 100644
--- a/src/comp/middle/trans_alt.rs
+++ b/src/comp/middle/trans_alt.rs
@@ -576,6 +576,7 @@ fn bind_irrefutable_pat(bcx: @block_ctxt, pat: @ast::pat, val: ValueRef,
             // FIXME: Could constrain pat_bind to make this
             // check unnecessary.
             check (type_has_static_size(ccx, ty));
+            check non_ty_var(ccx, ty);
             let llty = trans::type_of(ccx, pat.span, ty);
             let alloc = trans::alloca(bcx, llty);
             bcx =