diff --git a/test/cases/coroutines.zig b/test/cases/coroutines.zig
index 25a75dca5..922c1a7e5 100644
--- a/test/cases/coroutines.zig
+++ b/test/cases/coroutines.zig
@@ -56,6 +56,7 @@ var result = false;
 
 async fn testSuspendBlock() void {
     suspend |p| {
+        comptime assert(@typeOf(p) == promise->void);
         a_promise = p;
     }
     result = true;