diff --git a/test/async/async-calls-sync.wast b/test/async/async-calls-sync.wast
index 117be7b6..5d7508c4 100644
--- a/test/async/async-calls-sync.wast
+++ b/test/async/async-calls-sync.wast
@@ -53,18 +53,18 @@
       (export "context.set" (func $context.set))
       (export "context.get" (func $context.get))
     ))))
-    (func (export "blocking-call") (result u32) (canon lift
+    (func (export "blocking-call") async (result u32) (canon lift
       (core func $core_async_inner "blocking-call")
       async (callback (func $core_async_inner "blocking-call-cb"))
     ))
-    (func (export "unblock") (canon lift
+    (func (export "unblock") async (canon lift
       (core func $core_async_inner "unblock")
       async (callback (func $core_async_inner "unblock-cb"))
     ))
   )
 
   (component $SyncMiddle
-    (import "blocking-call" (func $blocking-call (result u32)))
+    (import "blocking-call" (func $blocking-call async (result u32)))
     (core module $CoreSyncMiddle
       (import "" "blocking-call" (func $blocking-call (result i32)))
       (func $sync-func (export "sync-func") (result i32)
@@ -75,13 +75,13 @@
     (core instance $core_sync_middle (instantiate $CoreSyncMiddle (with "" (instance
       (export "blocking-call" (func $blocking-call'))
     ))))
-    (func (export "sync-func") (result u32) (canon lift
+    (func (export "sync-func") async (result u32) (canon lift
       (core func $core_sync_middle "sync-func")
     ))
   )
 
   (component $AsyncMiddle
-    (import "blocking-call" (func $blocking-call (result u32)))
+    (import "blocking-call" (func $blocking-call async (result u32)))
     (core module $CoreSyncMiddle
       (import "" "task.return" (func $task.return (param i32)))
       (import "" "blocking-call" (func $blocking-call (result i32)))
@@ -99,16 +99,16 @@
       (export "task.return" (func $task.return))
       (export "blocking-call" (func $blocking-call'))
     ))))
-    (func (export "sync-func") (result u32) (canon lift
+    (func (export "sync-func") async (result u32) (canon lift
       (core func $core_sync_middle "sync-func")
       async (callback (func $core_sync_middle "sync-func-cb"))
     ))
   )
 
   (component $AsyncOuter
-    (import "unblock" (func $unblock))
-    (import "sync-func1" (func $sync-func1 (result u32)))
-    (import "sync-func2" (func $sync-func2 (result u32)))
+    (import "unblock" (func $unblock async))
+    (import "sync-func1" (func $sync-func1 async (result u32)))
+    (import "sync-func2" (func $sync-func2 async (result u32)))
 
     (core module $Memory (memory (export "mem") 1))
     (core instance $memory (instantiate $Memory))
@@ -219,7 +219,7 @@
       (export "sync-func1" (func $sync-func1'))
       (export "sync-func2" (func $sync-func2'))
     ))))
-    (func (export "run") (result u32) (canon lift
+    (func (export "run") async (result u32) (canon lift
       (core func $em "run")
       async (callback (func $em "run-cb"))
     ))
diff --git a/test/async/cancel-stream.wast b/test/async/cancel-stream.wast
index 128665a6..602a536a 100644
--- a/test/async/cancel-stream.wast
+++ b/test/async/cancel-stream.wast
@@ -81,20 +81,20 @@
       (export "stream.cancel-write" (func $stream.cancel-write))
       (export "stream.drop-writable" (func $stream.drop-writable))
     ))))
-    (func (export "start-stream") (result (stream u8)) (canon lift (core func $cm "start-stream")))
-    (func (export "write4") (canon lift (core func $cm "write4")))
-    (func (export "write4-and-drop") (canon lift (core func $cm "write4-and-drop")))
-    (func (export "start-blocking-write") (canon lift (core func $cm "start-blocking-write")))
-    (func (export "cancel-after-read4") (canon lift (core func $cm "cancel-after-read4")))
+    (func (export "start-stream") async (result (stream u8)) (canon lift (core func $cm "start-stream")))
+    (func (export "write4") async (canon lift (core func $cm "write4")))
+    (func (export "write4-and-drop") async (canon lift (core func $cm "write4-and-drop")))
+    (func (export "start-blocking-write") async (canon lift (core func $cm "start-blocking-write")))
+    (func (export "cancel-after-read4") async (canon lift (core func $cm "cancel-after-read4")))
   )
 
   (component $D
     (import "c" (instance $c
-      (export "start-stream" (func (result (stream u8))))
-      (export "write4" (func))
-      (export "write4-and-drop" (func))
-      (export "start-blocking-write" (func))
-      (export "cancel-after-read4" (func))
+      (export "start-stream" (func async (result (stream u8))))
+      (export "write4" (func async))
+      (export "write4-and-drop" (func async))
+      (export "start-blocking-write" (func async))
+      (export "cancel-after-read4" (func async))
     ))
 
     (core module $Memory (memory (export "mem") 1))
@@ -192,7 +192,7 @@
       (export "start-blocking-write" (func $start-blocking-write'))
       (export "cancel-after-read4" (func $cancel-after-read4'))
     ))))
-    (func (export "run") (result u32) (canon lift (core func $dm "run")))
+    (func (export "run") async (result u32) (canon lift (core func $dm "run")))
   )
 
   (instance $c (instantiate $C))
diff --git a/test/async/cancel-subtask.wast b/test/async/cancel-subtask.wast
index c90afc95..57a0f33e 100644
--- a/test/async/cancel-subtask.wast
+++ b/test/async/cancel-subtask.wast
@@ -70,19 +70,19 @@
       (export "waitable-set.new" (func $waitable-set.new))
       (export "waitable-set.wait" (func $waitable-set.wait))
     ))))
-    (func (export "f") (result u32) (canon lift
+    (func (export "f") async (result u32) (canon lift
       (core func $cm "f")
       async (callback (func $cm "f_cb"))
     ))
-    (func (export "g") (param "fut" $FT) (result u32) (canon lift
+    (func (export "g") async (param "fut" $FT) (result u32) (canon lift
       (core func $cm "g")
     ))
   )
 
   (component $D
     (type $FT (future))
-    (import "f" (func $f (result u32)))
-    (import "g" (func $g (param "fut" $FT) (result u32)))
+    (import "f" (func $f async (result u32)))
+    (import "g" (func $g async (param "fut" $FT) (result u32)))
 
     (core module $Memory (memory (export "mem") 1))
     (core instance $memory (instantiate $Memory))
@@ -188,7 +188,7 @@
       (export "f" (func $f'))
       (export "g" (func $g'))
     ))))
-    (func (export "run") (result u32) (canon lift (core func $dm "run")))
+    (func (export "run") async (result u32) (canon lift (core func $dm "run")))
   )
 
   (instance $c (instantiate $C))
diff --git a/test/async/deadlock.wast b/test/async/deadlock.wast
index e4697352..6d50c9f2 100644
--- a/test/async/deadlock.wast
+++ b/test/async/deadlock.wast
@@ -24,14 +24,14 @@
       (export "mem" (memory $memory "mem"))
       (export "waitable-set.new" (func $waitable-set.new))
     ))))
-    (func (export "f") (result u32) (canon lift
+    (func (export "f") async (result u32) (canon lift
       (core func $cm "f")
       async (memory $memory "mem") (callback (func $cm "cb"))
     ))
   )
 
   (component $D
-    (import "f" (func $f (result u32)))
+    (import "f" (func $f async (result u32)))
 
     (core module $Memory (memory (export "mem") 1))
     (core instance $memory (instantiate $Memory))
@@ -63,7 +63,7 @@
       (export "waitable-set.wait" (func $waitable-set.wait))
       (export "f" (func $f'))
     ))))
-    (func (export "f") (result u32) (canon lift (core func $dm "g")))
+    (func (export "f") async (result u32) (canon lift (core func $dm "g")))
   )
 
   (instance $c (instantiate $C))
diff --git a/test/async/drop-subtask.wast b/test/async/drop-subtask.wast
index ac4b988c..21eb9fcd 100644
--- a/test/async/drop-subtask.wast
+++ b/test/async/drop-subtask.wast
@@ -39,19 +39,19 @@
       (export "mem" (memory $memory "mem"))
       (export "task.return" (func $task.return))
     ))))
-    (func (export "loop") (canon lift
+    (func (export "loop") async (canon lift
       (core func $core_looper "loop")
       async (callback (func $core_looper "loop_cb"))
     ))
-    (func (export "return") (canon lift
+    (func (export "return") async (canon lift
       (core func $core_looper "return")
     ))
   )
 
   (component $Caller
     (import "looper" (instance $looper
-      (export "loop" (func))
-      (export "return" (func))
+      (export "loop" (func async))
+      (export "return" (func async))
     ))
 
     (core module $Memory (memory (export "mem") 1))
@@ -122,10 +122,10 @@
       (export "loop" (func $loop'))
       (export "return" (func $return'))
     ))))
-    (func (export "drop-after-return") (result u32) (canon lift
+    (func (export "drop-after-return") async (result u32) (canon lift
       (core func $core_caller "drop-after-return")
     ))
-    (func (export "drop-before-return") (result u32) (canon lift
+    (func (export "drop-before-return") async (result u32) (canon lift
       (core func $core_caller "drop-before-return")
     ))
   )
diff --git a/test/async/drop-waitable-set.wast b/test/async/drop-waitable-set.wast
index 285bbaf2..ce46bfd6 100644
--- a/test/async/drop-waitable-set.wast
+++ b/test/async/drop-waitable-set.wast
@@ -31,11 +31,11 @@
       (export "waitable-set.new" (func $waitable-set.new))
       (export "waitable-set.drop" (func $waitable-set.drop))
     ))))
-    (func (export "wait-on-set") (canon lift
+    (func (export "wait-on-set") async (canon lift
       (core func $core "wait-on-set")
       async (callback (func $core "unreachable-cb"))
     ))
-    (func (export "drop-while-waiting") (canon lift
+    (func (export "drop-while-waiting") async (canon lift
       (core func $core "drop-while-waiting")
       async (callback (func $core "unreachable-cb"))
     ))
@@ -43,8 +43,8 @@
 
   (component $D
     (import "c" (instance $c
-      (export "wait-on-set" (func))
-      (export "drop-while-waiting" (func))
+      (export "wait-on-set" (func async))
+      (export "drop-while-waiting" (func async))
     ))
 
     (core module $Memory (memory (export "mem") 1))
@@ -74,7 +74,7 @@
       (export "wait-on-set" (func $wait-on-set'))
       (export "drop-while-waiting" (func $drop-while-waiting'))
     ))))
-    (func (export "run") (result u32) (canon lift (core func $core "run")))
+    (func (export "run") async (result u32) (canon lift (core func $core "run")))
   )
 
   (instance $c (instantiate $C))
diff --git a/test/async/empty-wait.wast b/test/async/empty-wait.wast
index 601e3f4c..f8c743ef 100644
--- a/test/async/empty-wait.wast
+++ b/test/async/empty-wait.wast
@@ -102,11 +102,11 @@
       (export "future.drop-readable" (func $future.drop-readable))
       (export "future.drop-writable" (func $future.drop-writable))
     ))))
-    (func (export "blocker") (result u32) (canon lift
+    (func (export "blocker") async (result u32) (canon lift
       (core func $cm "blocker")
       async (callback (func $cm "blocker_cb"))
     ))
-    (func (export "unblocker") (result u32) (canon lift
+    (func (export "unblocker") async (result u32) (canon lift
       (core func $cm "unblocker")
       async (callback (func $cm "unblocker_cb"))
     ))
@@ -114,8 +114,8 @@
 
   (component $D
     (import "c" (instance $c
-      (export "blocker" (func (result u32)))
-      (export "unblocker" (func (result u32)))
+      (export "blocker" (func async (result u32)))
+      (export "unblocker" (func async (result u32)))
     ))
 
     (core module $Memory (memory (export "mem") 1))
@@ -189,7 +189,7 @@
       (export "blocker" (func $blocker'))
       (export "unblocker" (func $unblocker'))
     ))))
-    (func (export "run") (result u32) (canon lift (core func $dm "run")))
+    (func (export "run") async (result u32) (canon lift (core func $dm "run")))
   )
 
   (instance $c (instantiate $C))
diff --git a/test/async/partial-stream-copies.wast b/test/async/partial-stream-copies.wast
index 1151ba80..d25dd977 100644
--- a/test/async/partial-stream-copies.wast
+++ b/test/async/partial-stream-copies.wast
@@ -121,14 +121,14 @@
       (export "stream.drop-readable" (func $stream.drop-readable))
       (export "stream.drop-writable" (func $stream.drop-writable))
     ))))
-    (func (export "transform") (param "in" (stream u8)) (result (stream u8)) (canon lift
+    (func (export "transform") async (param "in" (stream u8)) (result (stream u8)) (canon lift
       (core func $cm "transform")
       async (memory $memory "mem") (callback (func $cm "transform_cb"))
     ))
   )
 
   (component $D
-    (import "transform" (func $transform (param "in" (stream u8)) (result (stream u8))))
+    (import "transform" (func $transform async (param "in" (stream u8)) (result (stream u8))))
 
     (core module $Memory (memory (export "mem") 1))
     (core instance $memory (instantiate $Memory))
@@ -228,7 +228,7 @@
       (export "stream.drop-writable" (func $stream.drop-writable))
       (export "transform" (func $transform'))
     ))))
-    (func (export "run") (result u32) (canon lift (core func $dm "run")))
+    (func (export "run") async (result u32) (canon lift (core func $dm "run")))
   )
 
   (instance $c (instantiate $C))
diff --git a/test/async/passing-resources.wast b/test/async/passing-resources.wast
index 395bb2ab..b4c996df 100644
--- a/test/async/passing-resources.wast
+++ b/test/async/passing-resources.wast
@@ -91,18 +91,18 @@
       (export "stream.drop-writable" (func $stream.drop-writable))
     ))))
     (export $R' "R" (type $R))
-    (func (export "[method]R.foo") (param "self" (borrow $R')) (result u32) (canon lift (core func $core "R.foo")))
-    (func (export "start-stream") (result (stream (own $R'))) (canon lift (core func $core "start-stream")))
-    (func (export "cancel-write") (canon lift (core func $core "cancel-write")))
-    (func (export "fail-accessing-res1") (canon lift (core func $core "fail-accessing-res1")))
+    (func (export "[method]R.foo") async (param "self" (borrow $R')) (result u32) (canon lift (core func $core "R.foo")))
+    (func (export "start-stream") async (result (stream (own $R'))) (canon lift (core func $core "start-stream")))
+    (func (export "cancel-write") async (canon lift (core func $core "cancel-write")))
+    (func (export "fail-accessing-res1") async (canon lift (core func $core "fail-accessing-res1")))
   )
 
   (component $Consumer
     (import "producer" (instance $producer
       (export "R" (type $R (sub resource)))
-      (export "[method]R.foo" (func (param "self" (borrow $R)) (result u32)))
-      (export "start-stream" (func (result (stream (own $R)))))
-      (export "cancel-write" (func))
+      (export "[method]R.foo" (func async (param "self" (borrow $R)) (result u32)))
+      (export "start-stream" (func async (result (stream (own $R)))))
+      (export "cancel-write" (func async))
     ))
 
     (core module $Memory (memory (export "mem") 1))
@@ -162,7 +162,7 @@
       (export "start-stream" (func $start-stream'))
       (export "cancel-write" (func $cancel-write'))
     ))))
-    (func (export "run") (result u32) (canon lift
+    (func (export "run") async (result u32) (canon lift
       (core func $core "run")
     ))
   )
diff --git a/test/async/trap-if-done.wast b/test/async/trap-if-done.wast
index 2555c0f5..5d7d9aa0 100644
--- a/test/async/trap-if-done.wast
+++ b/test/async/trap-if-done.wast
@@ -115,25 +115,25 @@
       (export "stream.write" (func $stream.write))
       (export "stream.drop-writable" (func $stream.drop-writable))
     ))))
-    (func (export "start-future") (result (future u8)) (canon lift (core func $cm "start-future")))
-    (func (export "future-write") (result u32) (canon lift (core func $cm "future-write")))
-    (func (export "acknowledge-future-write") (canon lift (core func $cm "acknowledge-future-write")))
-    (func (export "future-drop-writable") (canon lift (core func $cm "future-drop-writable")))
-    (func (export "start-stream") (result (stream u8)) (canon lift (core func $cm "start-stream")))
-    (func (export "stream-write") (result u32) (canon lift (core func $cm "stream-write")))
-    (func (export "acknowledge-stream-write") (canon lift (core func $cm "acknowledge-stream-write")))
-    (func (export "stream-drop-writable") (canon lift (core func $cm "stream-drop-writable")))
+    (func (export "start-future") async (result (future u8)) (canon lift (core func $cm "start-future")))
+    (func (export "future-write") async (result u32) (canon lift (core func $cm "future-write")))
+    (func (export "acknowledge-future-write") async (canon lift (core func $cm "acknowledge-future-write")))
+    (func (export "future-drop-writable") async (canon lift (core func $cm "future-drop-writable")))
+    (func (export "start-stream") async (result (stream u8)) (canon lift (core func $cm "start-stream")))
+    (func (export "stream-write") async (result u32) (canon lift (core func $cm "stream-write")))
+    (func (export "acknowledge-stream-write") async (canon lift (core func $cm "acknowledge-stream-write")))
+    (func (export "stream-drop-writable") async (canon lift (core func $cm "stream-drop-writable")))
   )
   (component $D
     (import "c" (instance $c
-      (export "start-future" (func (result (future u8))))
-      (export "future-write" (func (result u32)))
-      (export "acknowledge-future-write" (func))
-      (export "future-drop-writable" (func))
-      (export "start-stream" (func (result (stream u8))))
-      (export "stream-write" (func (result u32)))
-      (export "acknowledge-stream-write" (func))
-      (export "stream-drop-writable" (func))
+      (export "start-future" (func async (result (future u8))))
+      (export "future-write" (func async (result u32)))
+      (export "acknowledge-future-write" (func async))
+      (export "future-drop-writable" (func async))
+      (export "start-stream" (func async (result (stream u8))))
+      (export "stream-write" (func async (result u32)))
+      (export "acknowledge-stream-write" (func async))
+      (export "stream-drop-writable" (func async))
     ))
 
     (core module $Memory (memory (export "mem") 1))
@@ -417,15 +417,15 @@
       (export "acknowledge-stream-write" (func $acknowledge-stream-write'))
       (export "stream-drop-writable" (func $stream-drop-writable'))
     ))))
-    (func (export "trap-after-future-eager-write") (canon lift (core func $core "trap-after-future-eager-write")))
-    (func (export "trap-after-future-async-write") (canon lift (core func $core "trap-after-future-async-write")))
-    (func (export "trap-after-future-reader-dropped") (canon lift (core func $core "trap-after-future-reader-dropped")))
-    (func (export "trap-after-future-eager-read") (param "bool" bool) (result $FT) (canon lift (core func $core "trap-after-future-eager-read")))
-    (func (export "trap-after-future-async-read") (param "bool" bool) (result $FT) (canon lift (core func $core "trap-after-future-async-read")))
-    (func (export "trap-after-stream-reader-eager-dropped") (canon lift (core func $core "trap-after-stream-reader-eager-dropped")))
-    (func (export "trap-after-stream-reader-async-dropped") (canon lift (core func $core "trap-after-stream-reader-async-dropped")))
-    (func (export "trap-after-stream-writer-eager-dropped") (param "bool" bool) (result $ST) (canon lift (core func $core "trap-after-stream-writer-eager-dropped")))
-    (func (export "trap-after-stream-writer-async-dropped") (param "bool" bool) (result $ST) (canon lift (core func $core "trap-after-stream-writer-async-dropped")))
+    (func (export "trap-after-future-eager-write") async (canon lift (core func $core "trap-after-future-eager-write")))
+    (func (export "trap-after-future-async-write") async (canon lift (core func $core "trap-after-future-async-write")))
+    (func (export "trap-after-future-reader-dropped") async (canon lift (core func $core "trap-after-future-reader-dropped")))
+    (func (export "trap-after-future-eager-read") async (param "bool" bool) (result $FT) (canon lift (core func $core "trap-after-future-eager-read")))
+    (func (export "trap-after-future-async-read") async (param "bool" bool) (result $FT) (canon lift (core func $core "trap-after-future-async-read")))
+    (func (export "trap-after-stream-reader-eager-dropped") async (canon lift (core func $core "trap-after-stream-reader-eager-dropped")))
+    (func (export "trap-after-stream-reader-async-dropped") async (canon lift (core func $core "trap-after-stream-reader-async-dropped")))
+    (func (export "trap-after-stream-writer-eager-dropped") async (param "bool" bool) (result $ST) (canon lift (core func $core "trap-after-stream-writer-eager-dropped")))
+    (func (export "trap-after-stream-writer-async-dropped") async (param "bool" bool) (result $ST) (canon lift (core func $core "trap-after-stream-writer-async-dropped")))
   )
   (instance $c (instantiate $C))
   (instance $d (instantiate $D (with "c" (instance $c))))
diff --git a/test/async/wait-during-callback.wast b/test/async/wait-during-callback.wast
index eb50bbf8..3f95d5b1 100644
--- a/test/async/wait-during-callback.wast
+++ b/test/async/wait-during-callback.wast
@@ -69,7 +69,7 @@
     (export "future.read" (func $future.read))
     (export "future.write" (func $future.write))
   ))))
-  (func (export "run") (result u32) (canon lift
+  (func (export "run") async (result u32) (canon lift
     (core func $cm "run")
     async (callback (func $cm "run_cb"))
   ))
diff --git a/test/async/zero-length.wast b/test/async/zero-length.wast
index a75978f4..fab7765f 100644
--- a/test/async/zero-length.wast
+++ b/test/async/zero-length.wast
@@ -104,7 +104,7 @@
       (export "stream.write" (func $stream.write))
       (export "stream.drop-writable" (func $stream.drop-writable))
     ))))
-    (func (export "produce") (result (stream u8)) (canon lift
+    (func (export "produce") async (result (stream u8)) (canon lift
       (core func $core_producer "produce")
       async (callback (func $core_producer "produce_cb"))
     ))
@@ -184,15 +184,15 @@
       (export "stream.read" (func $stream.read))
       (export "stream.drop-readable" (func $stream.drop-readable))
     ))))
-    (func (export "consume") (param "in" (stream u8)) (result u32) (canon lift
+    (func (export "consume") async (param "in" (stream u8)) (result u32) (canon lift
       (core func $core_consumer "consume")
       async (callback (func $core_consumer "consume_cb"))
     ))
   )
 
   (component $Parent
-    (import "produce" (func $produce (result (stream u8))))
-    (import "consume" (func $consume (param "in" (stream u8)) (result u32)))
+    (import "produce" (func $produce async (result (stream u8))))
+    (import "consume" (func $consume async (param "in" (stream u8)) (result u32)))
 
     (core module $CoreParent
       (import "" "produce" (func $produce (result i32)))
@@ -209,7 +209,7 @@
       (export "produce" (func $produce'))
       (export "consume" (func $consume'))
     ))))
-    (func (export "run") (result u32) (canon lift (core func $core_parent "run")))
+    (func (export "run") async (result u32) (canon lift (core func $core_parent "run")))
   )
 
   (instance $producer (instantiate $Producer))