diff --git a/capnp/includes/capnp_cpp.pxd b/capnp/includes/capnp_cpp.pxd
index e4f5675..9e4f437 100644
--- a/capnp/includes/capnp_cpp.pxd
+++ b/capnp/includes/capnp_cpp.pxd
@@ -101,7 +101,14 @@ ctypedef Promise[PyArray] PyPromiseArray
 
 cdef extern from "kj/time.h" namespace " ::kj":
     cdef cppclass Duration:
-        Duration(int64_t)
+        Duration operator*(int64_t)
+    Duration NANOSECONDS
+    Duration MICROSECONDS
+    Duration MILLISECONDS
+    Duration SECONDS
+    Duration MINUTES
+    Duration HOURS
+    Duration DAYS
     # cdef cppclass TimePoint:
     #     TimePoint(Duration)
     cdef cppclass Timer:
@@ -109,6 +116,9 @@ cdef extern from "kj/time.h" namespace " ::kj":
         # VoidPromise atTime(TimePoint time)
         VoidPromise afterDelay(Duration delay)
 
+cdef inline Duration Nanoseconds(int64_t nanos):
+    return NANOSECONDS * nanos
+
 cdef extern from "kj/async-io.h" namespace " ::kj":
     cdef cppclass AsyncIoStream:
         pass
diff --git a/capnp/lib/capnp.pyx b/capnp/lib/capnp.pyx
index f25eb6c..aa23137 100644
--- a/capnp/lib/capnp.pyx
+++ b/capnp/lib/capnp.pyx
@@ -1688,7 +1688,7 @@ cdef class _Timer:
         return self
 
     cpdef after_delay(self, time) except +reraise_kj_exception:
-        return _VoidPromise()._init(self.thisptr.afterDelay(capnp.Duration(time)))
+        return _VoidPromise()._init(self.thisptr.afterDelay(capnp.Nanoseconds(time)))
 
 def getTimer():
     return _Timer()._init(helpers.getTimer(C_DEFAULT_EVENT_LOOP_GETTER().thisptr))