diff --git a/src/syscall/zx/types.go b/src/syscall/zx/types.go
index f624bc4..47ca623 100644
--- a/src/syscall/zx/types.go
+++ b/src/syscall/zx/types.go
@@ -11,8 +11,8 @@
 type Status int32    // zx_status_t
 type Handle uint32   // zx_handle_t
 type Clock uint32    // zx_clock_t,
-type Time uint64     // zx_time_t, nanoseconds
-type Duration uint64 // zx_duration_t, nanoseconds
+type Time int64      // zx_time_t, nanoseconds
+type Duration int64  // zx_duration_t, nanoseconds
 type Signals uint32  // zx_signals_t
 type Rights uint32   // zx_rights_t
 type Paddr uintptr   // zx_paddr_t
@@ -392,7 +392,7 @@
 )
 
 const (
-	TimensecInfinite = Time(0xFFFFFFFFFFFFFFFF)
+	TimensecInfinite = Time(0x7FFFFFFFFFFFFFFF)
 )
 
 // EOF is used like io.EOF.