diff --git a/libs/base/System/Concurrency/Raw.idr b/libs/base/System/Concurrency/Raw.idr
index 38f488612..663e2757f 100644
--- a/libs/base/System/Concurrency/Raw.idr
+++ b/libs/base/System/Concurrency/Raw.idr
@@ -55,7 +55,7 @@ data Condition : Type where [external]
 prim__makeCondition : PrimIO Condition
 %foreign "scheme:blodwen-condition-wait"
 prim__conditionWait : Condition -> Mutex -> PrimIO ()
-%foreign "scheme:blodwen-condition-wait-timoue"
+%foreign "scheme:blodwen-condition-wait-timeout"
 prim__conditionWaitTimeout : Condition -> Mutex -> Int -> PrimIO ()
 %foreign "scheme:blodwen-condition-signal"
 prim__conditionSignal : Condition -> PrimIO ()
@@ -70,6 +70,7 @@ export
 conditionWait : Condition -> Mutex -> IO ()
 conditionWait c m = primIO (prim__conditionWait c m)
 
+||| Timeout is in microseconds
 export
 conditionWaitTimeout : Condition -> Mutex -> Int -> IO ()
 conditionWaitTimeout c m t = primIO (prim__conditionWaitTimeout c m t)
diff --git a/libs/prelude/PrimIO.idr b/libs/prelude/PrimIO.idr
index 6f1e7924d..4ccacf5d6 100644
--- a/libs/prelude/PrimIO.idr
+++ b/libs/prelude/PrimIO.idr
@@ -108,7 +108,7 @@ unsafeDestroyWorld : (1 x : %World) -> a -> a
 unsafeDestroyWorld %MkWorld x = x
 
 export
-unsafePerformIO : IO a -> a
+unsafePerformIO : (1 _ : IO a) -> a
 unsafePerformIO (MkIO f)
     = unsafeCreateWorld (\w => case f w of
                                MkIORes res w' => unsafeDestroyWorld w' res)
diff --git a/support/chez/support.ss b/support/chez/support.ss
index 79a069874..58ba1d140 100644
--- a/support/chez/support.ss
+++ b/support/chez/support.ss
@@ -183,7 +183,10 @@
 
 (define (blodwen-condition) (make-condition))
 (define (blodwen-condition-wait c m) (condition-wait c m))
-(define (blodwen-condition-wait-timeout c m t) (condition-wait c m t))
+(define (blodwen-condition-wait-timeout c m t)
+  (let ((sec (div t 1000000))
+        (micro (mod t 1000000)))
+  (condition-wait c m (make-time 'time-duration (* 1000 micro) sec))))
 (define (blodwen-condition-signal c) (condition-signal c))
 (define (blodwen-condition-broadcast c) (condition-broadcast c))
 
diff --git a/support/racket/support.rkt b/support/racket/support.rkt
index a3bea5b2c..2f29ed9cd 100644
--- a/support/racket/support.rkt
+++ b/support/racket/support.rkt
@@ -180,7 +180,7 @@
   (blodwen-lock m))
 (define (blodwen-condition-wait-timeout c m t)
   (blodwen-unlock m) ;; consistency with interface for posix condition variables
-  (sync/timeout t c)
+  (sync/timeout (/ t 1000000) c)
   (blodwen-lock m))
 (define (blodwen-condition-signal c)
   (channel-put c 'ready))