diff --git a/src/cuda/cudnn.jl b/src/cuda/cudnn.jl
index 72246a85..7929c6e2 100644
--- a/src/cuda/cudnn.jl
+++ b/src/cuda/cudnn.jl
@@ -1,4 +1,5 @@
-using CuArrays.CUDNN: @check, libcudnn, cudnnStatus_t, libcudnn_handle, cudnnDataType
+using CuArrays.CUDNN: @check, libcudnn, cudnnStatus_t, libcudnn_handle,
+  cudnnDataType, TensorDesc
 
 mutable struct DropoutDesc
   ptr::Ptr{Void}
@@ -49,7 +50,7 @@ function RNNDesc(T, mode, input, hidden; layers = 1)
   finalizer(rd, x ->
     @check ccall((:cudnnDestroyRNNDescriptor,libcudnn),cudnnStatus_t,(Ptr{Void},),x))
 
-  dropoutDesc = DropoutDesc()
+  dropoutDesc = DropoutDesc(0)
   inputMode = LINEAR_INPUT
   direction = UNIDIRECTIONAL
   algo = RNN_ALGO_STANDARD
@@ -57,3 +58,10 @@ function RNNDesc(T, mode, input, hidden; layers = 1)
     libcudnn_handle[],rd,hidden,layers,dropoutDesc,inputMode,direction,mode,algo,cudnnDataType(T))
   return rd
 end
+
+function rnnParamSize(r::RNNDesc, x)
+  size = Csize_t[0]
+  @check ccall((:cudnnGetRNNParamsSize, libcudnn), cudnnStatus_t, (Ptr{Void},Ptr{Void},Ptr{Void},Ptr{Csize_t},Cint),
+    libcudnn_handle[], r, TensorDesc(x), size, cudnnDataType(eltype(x)))
+  return Int(size[])
+end