diff --git a/test/stage1/behavior/union.zig b/test/stage1/behavior/union.zig
index d831b51b08c1..a977e318533f 100644
--- a/test/stage1/behavior/union.zig
+++ b/test/stage1/behavior/union.zig
@@ -611,3 +611,12 @@ test "function call result coerces from tagged union to the tag" {
     S.doTheTest();
     comptime S.doTheTest();
 }
+
+test "0-sized extern union definition" {
+    const U = extern union {
+        a: void,
+        const f = 1;
+    };
+
+    expect(U.f == 1);
+}