diff --git a/info2praktikum-neuronalesnetz/matrix.c b/info2praktikum-neuronalesnetz/matrix.c
index d3037b6..8ec59fd 100644
--- a/info2praktikum-neuronalesnetz/matrix.c
+++ b/info2praktikum-neuronalesnetz/matrix.c
@@ -61,8 +61,8 @@ Matrix add(const Matrix matrix1, const Matrix matrix2)
     }
 
     Matrix result = createMatrix(matrix1.rows, matrix1.cols);
-    for (unsigned int i = 0; i < matrix1.rows; i++) {
-      for (unsigned int j = 0; j < matrix1.cols; j++) {
+    for (size_t i = 0; i < matrix1.rows; i++) {
+      for (size_t j = 0; j < matrix1.cols; j++) {
         MatrixType sum = getMatrixAt(matrix1, i, j) + getMatrixAt(matrix2, i, j);
         setMatrixAt(sum, result, i, j);
       }