diff --git a/src/Effect/Aff.js b/src/Effect/Aff.js
index 83ba852..ff8bca2 100644
--- a/src/Effect/Aff.js
+++ b/src/Effect/Aff.js
@@ -327,6 +327,12 @@ var Aff = function () {
                 }
                 runTick++;
                 Scheduler.enqueue(function () {
+                  // It's possible to interrupt the fiber between enqueuing and
+                  // resuming, so we need to check that the runTick is still
+                  // valid.
+                  if (runTick !== localRunTick + 1) {
+                    return;
+                  }
                   status = STEP_RESULT;
                   step   = result;
                   run(runTick);
diff --git a/test/Test/Main.purs b/test/Test/Main.purs
index c21a71b..4f70574 100644
--- a/test/Test/Main.purs
+++ b/test/Test/Main.purs
@@ -660,6 +660,13 @@ test_regression_bracket_catch_cleanup = assert "regression/bracket-catch-cleanup
       (\_ → throwError (error "Nope."))
   pure $ lmap message res == Left "Nope."
 
+test_regression_kill_sync_async ∷ Aff Unit
+test_regression_kill_sync_async = assert "regression/kill-sync-async" do
+  ref ← newRef ""
+  f1 ← forkAff $ makeAff \k -> k (Left (error "Boom.")) *> mempty
+  killFiber (error "Nope.") f1
+  pure true
+
 main ∷ Effect Unit
 main = do
   test_pure
@@ -707,3 +714,4 @@ main = do
     test_regression_return_fork
     test_regression_par_apply_async_canceler
     test_regression_bracket_catch_cleanup
+    test_regression_kill_sync_async