diff --git a/src/layers/normalisation.jl b/src/layers/normalisation.jl
index a105e1ba..f7a425b2 100644
--- a/src/layers/normalisation.jl
+++ b/src/layers/normalisation.jl
@@ -92,12 +92,12 @@ function (BN::BatchNorm)(x)
     ϵ = T(BN.ϵ)
     m = size(x, 2)  # batch size
     μ = sum(x, 2) ./ m
-    σ = sqrt.(sum((x .- μ).^2, 2) ./ (m - 1) .+ ϵ)
+    σ = sqrt.(sum((x .- μ).^2, 2) ./ m .+ ϵ)
 
     # update moving mean/std
     mtm = T(BN.momentum)
-    BN.μ = mtm .* μ.data .+ (1 - mtm) .* BN.μ
-    BN.σ = mtm .* σ.data .+ (1 - mtm) .* BN.σ
+    BN.μ = (1 - mtm) .* BN.μ .+ mtm .* μ.data
+    BN.σ = (1 - mtm) .* BN.σ .+ mtm .* σ.data .* m ./ (m - 1)
   end
 
   BN.λ.(BN.γ .* ((x .- μ) ./ σ) .+ BN.β)