diff --git a/lib/std/Io/Uring.zig b/lib/std/Io/Uring.zig
index 59d932311384d4e3de96ef51d618e61338e4783c..58d97dc0e8e090c84bec204f74be93a8bd5e5c37 100644
--- a/lib/std/Io/Uring.zig
+++ b/lib/std/Io/Uring.zig
@@ -1135,8 +1135,9 @@ fn mainIdleEntry() callconv(.naked) void {
 
 fn mainIdle(
     ev: *Evented,
-    message: *const SwitchMessage,
+    contexts: *const Io.fiber.Switch,
 ) callconv(.withStackAlign(.c, @max(@alignOf(Thread), @alignOf(Io.fiber.Context)))) noreturn {
+    const message: *const SwitchMessage = @fieldParentPtr("contexts", contexts);
     message.handle(ev);
     ev.idle(&ev.threads.allocated[0]);
     ev.yield(@ptrCast(&ev.main_fiber_buffer), .nothing);
@@ -1414,8 +1415,9 @@ const AsyncClosure = struct {
 
     fn call(
         closure: *AsyncClosure,
-        message: *const SwitchMessage,
+        contexts: *const Io.fiber.Switch,
     ) callconv(.withStackAlign(.c, @alignOf(AsyncClosure))) noreturn {
+        const message: *const SwitchMessage = @fieldParentPtr("contexts", contexts);
         const ev = closure.evented;
         const fiber = closure.fiber;
         message.handle(ev);
@@ -1779,8 +1781,9 @@ const Group = struct {
 
         fn call(
             closure: *Group.AsyncClosure,
-            message: *const SwitchMessage,
+            contexts: *const Io.fiber.Switch,
         ) callconv(.withStackAlign(.c, @alignOf(Group.AsyncClosure))) noreturn {
+            const message: *const SwitchMessage = @fieldParentPtr("contexts", contexts);
             const ev = closure.evented;
             const fiber = closure.fiber;
             message.handle(ev);