diff --git a/src/test_conjugate_gradient.cpp b/src/test_conjugate_gradient.cpp
index d94a83d2b0109eea9d308876f9a8c55727d89da3..03caeb6e23d146f7fa6592f92ea0cce12435a104 100644
--- a/src/test_conjugate_gradient.cpp
+++ b/src/test_conjugate_gradient.cpp
@@ -20,8 +20,8 @@ TEST_CASE("Minimization via conjugated gradient method on functions with "
     using std::cout;
     using std::endl;
     FivePointDifferentiator fp;
-    double step = 1e-6;
-    ConjugateGradient optimizer(fp, step);
+    double diff_precision = 1e-6;
+    ConjugateGradient optimizer(fp, diff_precision);
 
     Coordinate<double> position1(1), position2(2), ref2(2), res1(1), res2(2);
 
diff --git a/src/test_gradient_descent.cpp b/src/test_gradient_descent.cpp
index 9e8b9e716c3eca4829dde8ac2d9cd002da06c754..972ae76ebbf751614b97d0f4b18c463a6f8ea7b9 100644
--- a/src/test_gradient_descent.cpp
+++ b/src/test_gradient_descent.cpp
@@ -20,7 +20,8 @@ TEST_CASE("Gradient Descent on functions with multi-dimensional argument",
     using std::endl;
     FivePointDifferentiator fp;
     double step = 1e-4;
-    GradientDescent optimizer(fp, step);
+    double diff_precision = 1e-6;
+    GradientDescent optimizer(fp, step, diff_precision);
 
     Coordinate<double> position1(1), position2(2), ref2(2), res1(1), res2(2);
 
diff --git a/src/test_gradient_root.cpp b/src/test_gradient_root.cpp
index 70f54d80dcc31d2f261d8ecaa9c4be73c25649fb..bcd25cfdf8dd1e510a4ed36a5bd2e71b284d3f2c 100644
--- a/src/test_gradient_root.cpp
+++ b/src/test_gradient_root.cpp
@@ -20,8 +20,8 @@ TEST_CASE("Minimization via gradient root finding on functions with "
     using std::cout;
     using std::endl;
     FivePointDifferentiator fp;
-    double step = 1e-6;
-    GradientRootfinder optimizer(fp, step);
+    double diff_precision = 1e-6;
+    GradientRootfinder optimizer(fp, diff_precision);
 
     Coordinate<double> position1(1), position2(2), ref2(2), res1(1), res2(2);