diff --git a/src/model.jl b/src/model.jl
index b0004d800..51d7bd5da 100644
--- a/src/model.jl
+++ b/src/model.jl
@@ -586,20 +586,22 @@ function fit(self :: FeedForward, optimizer :: AbstractOptimizer, data :: Abstra
   nothing
 end
 
-function save_checkpoint(self :: FeedForward, prefix :: AbstractString, state :: OptimizationState)
+save_checkpoint(self::FeedForward, prefix::AbstractString, state::OptimizationState) =
   save_checkpoint(self.arch, self.arg_params, self.aux_params, prefix, state.curr_epoch)
-end
-function save_checkpoint(sym :: SymbolicNode, arg_params :: Dict{Base.Symbol, NDArray},
-                         aux_params :: Dict{Base.Symbol, NDArray}, prefix :: AbstractString, epoch :: Int)
+
+function save_checkpoint(sym::SymbolicNode, arg_params::Dict{Symbol},
+                         aux_params::Dict{Symbol}, prefix::AbstractString, epoch::Int)
   save("$prefix-symbol.json", sym)
-  save_dict = merge(Dict{Base.Symbol, NDArray}(map((x) -> Symbol("arg:$(x[1])") => x[2], arg_params)),
-                    Dict{Base.Symbol, NDArray}(map((x) -> Symbol("aux:$(x[1])") => x[2], aux_params)))
+  save_dict = Dict{Symbol, NDArray}(map((x) -> Symbol("arg:$(x[1])") => x[2], arg_params))
+  if !isempty(aux_params)
+    merge!(save_dict, Dict(map((x) -> Symbol("aux:$(x[1])") => x[2], aux_params)))
+  end
   save_filename = format("{1}-{2:04d}.params", prefix, epoch)
   save(save_filename, save_dict)
   info("Saved checkpoint to '$save_filename'")
 end
 
-function load_checkpoint(prefix :: AbstractString, epoch :: Int)
+function load_checkpoint(prefix::AbstractString, epoch::Int)
   arch       = load("$prefix-symbol.json", SymbolicNode)
   saved_dict = load(format("{1}-{2:04d}.params", prefix, epoch), NDArray)
   arg_params = Dict{Base.Symbol, NDArray}()