diff --git a/src/layers/basic.jl b/src/layers/basic.jl
index 088cf1e1..0c7e1fd0 100644
--- a/src/layers/basic.jl
+++ b/src/layers/basic.jl
@@ -115,6 +115,13 @@ function (a::Dropout)(x)
   end
 end
 
+"""
+    setmode!(m, mode::Symbol)
+
+Change the mode of model `m` to `mode`. Possible values for `mode` are
+`:train` and `:eval`.
+This has an affect only if `m` contains [`Dropout`](@ref) of `BatchNorm` layers.
+"""
 setmode!(a, mode::Symbol) = nothing
 setmode!(c::Chain, mode::Symbol) = mapchildren(x->setmode!(x, mode), c)
 setmode!(a::Dropout, mode::Symbol) = a.mode = mode
diff --git a/src/tracker/Tracker.jl b/src/tracker/Tracker.jl
index a2a6c745..8f495f82 100644
--- a/src/tracker/Tracker.jl
+++ b/src/tracker/Tracker.jl
@@ -1,5 +1,5 @@
 module Tracker
-
+import Base: <, ==
 export TrackedArray, param, back!
 
 data(x) = x
@@ -54,6 +54,13 @@ Base.similar(x::TrackedArray, dims::Union{AbstractUnitRange,Integer}...) =
 
 Base.similar(x::TrackedArray, T::Type) = similar(data(x), T)
 
+==(x::TrackedArray, y) = data(x) == y
+==(y, x::TrackedArray) = y == data(x)
+==(x::TrackedScalar, y) = data(x)[] == y
+==(y, x::TrackedScalar) = y == data(x)[]
+<(x::TrackedScalar, y) = data(x)[] < y
+<(x, y::TrackedScalar) = x <  data(y)[]
+
 Base.show(io::IO, ::Type{TrackedArray{T,N,A}}) where {T,N,A<:AbstractArray{T,N}} =
   print(io, "TrackedArray{…,$A}")
 
diff --git a/test/layers.jl b/test/layers.jl
index ead9c343..d0a5cbe1 100644
--- a/test/layers.jl
+++ b/test/layers.jl
@@ -16,8 +16,8 @@
   m = Chain(Dense(100,100),
             Dropout(0.9))
   y = m(x)
-  @test count(a->a.data[] == 0, y) > 50
+  @test count(a->a == 0, y) > 50
   setmode!(m, :eval)
   y = m(x)
-  @test count(a->a.data[] == 0, y) == 0
+  @test count(a->a == 0, y) == 0
 end