diff --git a/test/standalone.zig b/test/standalone.zig
index 29a32d878f4c1bd1d4acb26144a0e3b4c07e8a13..4cf795a85f008c7e0501d214bd958970240fbd8c 100644
--- a/test/standalone.zig
+++ b/test/standalone.zig
@@ -147,6 +147,10 @@ pub const build_cases = [_]BuildCase{
         .build_root = "test/standalone/embed_generated_file",
         .import = @import("standalone/embed_generated_file/build.zig"),
     },
+    .{
+        .build_root = "test/standalone/extern",
+        .import = @import("standalone/extern/build.zig"),
+    },
     .{
         .build_root = "test/standalone/dep_diamond",
         .import = @import("standalone/dep_diamond/build.zig"),
diff --git a/test/standalone/extern/build.zig b/test/standalone/extern/build.zig
index 8a44a6ca8f9e767ed9ae6320213178846522aecc..153380e91ded1b36891c41f2318caf150726b05c 100644
--- a/test/standalone/extern/build.zig
+++ b/test/standalone/extern/build.zig
@@ -1,7 +1,7 @@
 const std = @import("std");
 
 pub fn build(b: *std.Build) void {
-    const optimize = b.standardOptimizeOption(.{});
+    const optimize: std.builtin.OptimizeMode = .Debug;
 
     const obj = b.addObject(.{
         .name = "exports",