diff --git a/src/functions/activation_functions.rs b/src/functions/activation_functions.rs
index d233ffb..074166c 100644
--- a/src/functions/activation_functions.rs
+++ b/src/functions/activation_functions.rs
@@ -44,7 +44,7 @@ pub fn logistic(matrix: &Array1<f64>) -> Array1<f64> {
 
 pub fn logistic_prime(matrix: &Array1<f64>) -> Array1<f64> {
     let mut result = matrix.clone();
-    result.mapv_inplace(|x| sigmoid(x * (1.0 - sigmoid(x))));
+    result.mapv_inplace(|x| sigmoid(x) * (1.0 - sigmoid(x)));
     result
 }