diff --git a/src/compiler/execution.jl b/src/compiler/execution.jl
index 1fd4f3b9..75339ceb 100644
--- a/src/compiler/execution.jl
+++ b/src/compiler/execution.jl
@@ -84,7 +84,7 @@ macro metal(ex...)
                 $kernel_tt = Tuple{map(Core.Typeof, $kernel_args)...}
                 $kernel = $mtlfunction($kernel_f, $kernel_tt; $(compiler_kwargs...))
                 if $launch
-                    $kernel($(var_exprs...); $(call_kwargs...))
+                    $kernel($kernel_args...; $(call_kwargs...))
                 end
                 $kernel
             end
@@ -203,7 +203,7 @@ const _kernel_instances = Dict{UInt, Any}()
 
 ## kernel launching and argument encoding
 
-@inline @generated function encode_arguments!(cce, kernel, args...)
+@inline @generated function encode_arguments!(cce, kernel::HostKernel{F,TT}, args...) where {F,TT}
     ex = quote
         bufs = MTLBuffer[]
     end
@@ -216,6 +216,8 @@ const _kernel_instances = Dict{UInt, Any}()
     idx = 1
     for (argidx, argtyp) in enumerate(args)
         argex = :(args[$argidx])
+        argTT = :(TT.parameters[$argidx])
+
         if argtyp <: MTLBuffer
             # top-level buffers are passed as a pointer-valued argument
             push!(ex.args, :(set_buffer!(cce, $argex, 0, $idx)))
@@ -227,7 +229,11 @@ const _kernel_instances = Dict{UInt, Any}()
         else
             # everything else is passed by reference, in an argument buffer
             append!(ex.args, (quote
-                buf = encode_argument!(kernel, mtlconvert($(argex), cce))
+                buf = if $argtyp != $argTT
+                    encode_argument!(kernel, mtlconvert($(argex), cce))
+                else
+                    encode_argument!(kernel, $argex)
+                end
                 set_buffer!(cce, buf, 0, $idx)
                 push!(bufs, buf)
             end).args)
@@ -259,8 +265,7 @@ end
     return argument_buffer
 end
 
-@autoreleasepool function (kernel::HostKernel)(args...; groups=1, threads=1,
-                                               queue=global_queue(device()))
+@autoreleasepool function (kernel::HostKernel)(args...; groups=1, threads=1, queue=global_queue(device()))
     groups = MTLSize(groups)
     threads = MTLSize(threads)
     (groups.width>0 && groups.height>0 && groups.depth>0) ||
@@ -276,7 +281,7 @@ end
     cce = MTLComputeCommandEncoder(cmdbuf)
     argument_buffers = try
         MTL.set_function!(cce, kernel.pipeline)
-        bufs = encode_arguments!(cce, kernel, kernel.f, args...)
+        bufs = encode_arguments!(cce, kernel, args...)
         MTL.append_current_function!(cce, groups, threads)
         bufs
     finally