diff --git a/cl/builtin_test.go b/cl/builtin_test.go
index bf83a119..a3fa722a 100644
--- a/cl/builtin_test.go
+++ b/cl/builtin_test.go
@@ -25,6 +25,16 @@ import (
 	"golang.org/x/tools/go/ssa"
 )
 
+func TestErrAlloca(t *testing.T) {
+	defer func() {
+		if r := recover(); r == nil {
+			t.Fatal("alloca: no error?")
+		}
+	}()
+	var ctz context
+	ctz.alloca(nil, nil)
+}
+
 func TestCStrNoArgs(t *testing.T) {
 	defer func() {
 		if r := recover(); r == nil {