diff --git a/src/stdlib/statistics.jl b/src/stdlib/statistics.jl
index 70cb42a..069b484 100644
--- a/src/stdlib/statistics.jl
+++ b/src/stdlib/statistics.jl
@@ -39,7 +39,7 @@ get the pdf of `Normal(μ, σ)` at point `x`.
         anc1 += x
         anc1 -= μ
         anc2 += anc1 / σ  # (x- μ)/σ
-        anc3 += anc2 * anc2 # (x-μ)^2/σ^2
+        anc3 += anc2^2 # (x-μ)^2/σ^2
     end
 
     out -= anc3 * 0.5 # -(x-μ)^2/2σ^2
diff --git a/test/autodiff/hessian_backback.jl b/test/autodiff/hessian_backback.jl
index bc4290f..c7f998c 100644
--- a/test/autodiff/hessian_backback.jl
+++ b/test/autodiff/hessian_backback.jl
@@ -11,7 +11,7 @@ using NiLang.AD: hessian_numeric
         a += b^d
         c += b/d
         ROT(a, c, d)
-        b += d * d
+        b += d ^ 2
         a += c * d
     end
     h1 = hessian_backback(test, (0.0, 2.0, 1.0, 3.0); iloss=1)