diff --git a/histogram.cpp b/histogram.cpp
index 2d35027..71b6fc5 100644
--- a/histogram.cpp
+++ b/histogram.cpp
@@ -1,11 +1,10 @@
 #include "histogram.h"
 #include <vector>
 #include "histogram_internal.h"
-void find_minmax(const std::vector <double> &numbers, double &min, double &max, bool &res)
+void find_minmax(const std::vector <double> &numbers, double &min, double &max)
 {
     if (numbers.size()==0)
     {
-        res = true;
         return;
     }
     min = numbers[0];
@@ -26,7 +25,7 @@ std::vector<std::size_t> make_histogram(const std::vector<double> &numbers, std:
 {
     double min, max;
     bool res = false;
-    find_minmax(numbers, min, max, res);
+    find_minmax(numbers, min, max);
     double bin_size = (max - min) / bin_count;
     std::vector <std::size_t> bins (bin_count);
 
diff --git a/histogram_internal.h b/histogram_internal.h
index 44594cb..a4eddaa 100644
--- a/histogram_internal.h
+++ b/histogram_internal.h
@@ -3,6 +3,6 @@
 
 #include <vector>
 
-void find_minmax(const std::vector <double> &numbers, double &min, double &max, bool &res);
+void find_minmax(const std::vector <double> &numbers, double &min, double &max);
 
 #endif // HISTOGRAM_INTERNAL_H_INCLUDED
diff --git a/main.cpp b/main.cpp
index 5677ea7..92cb303 100644
--- a/main.cpp
+++ b/main.cpp
@@ -30,7 +30,6 @@ input_data()
 int
 main()
 {
-    bool res = false;
     Input in = input_data();
     auto bins = make_histogram(in.numbers, in.bin_count);
     show_histogram_svg(bins);
diff --git a/unittest.cpp b/unittest.cpp
index 3cfebd4..966bf30 100644
--- a/unittest.cpp
+++ b/unittest.cpp
@@ -6,52 +6,35 @@
 
 
 TEST_CASE("distinct positive numbers") {
-    bool res = false;
     double min = 0;
     double max = 0;
-    find_minmax({1, 2}, min, max, res);
+    find_minmax({1, 2}, min, max);
     CHECK(min == 1);
     CHECK(max == 2);
-    CHECK(res==0);
 }
 
 TEST_CASE("negative numbers") {
-    bool res = false;
     double min = 0;
     double max = 0;
-    find_minmax({-1, -2}, min, max, res);
+    find_minmax({-1, -2}, min, max);
     CHECK(min == -2);
     CHECK(max == -1);
-    CHECK(res==0);
 }
 
-TEST_CASE("empty array") {
-    bool res = false;
+TEST_CASE("empty vector") {
     double min = 0;
     double max = 0;
     std::vector<double> numbers;
-    find_minmax(numbers, min, max, res);
+    find_minmax(numbers, min, max);
     CHECK(min == 0);
     CHECK(max == 0);
-    CHECK(res==1);
 }
 
 TEST_CASE("1 number") {
-    bool res = false;
     double min = 0;
     double max = 0;
-    find_minmax({-1}, min, max, res);
+    find_minmax({-1}, min, max);
     CHECK(min == -1);
     CHECK(max == -1);
-    CHECK(res==0);
 }
 
-TEST_CASE("same number") {
-    bool res = false;
-    double min = 0;
-    double max = 0;
-    find_minmax({1,1,1,1}, min, max, res);
-    CHECK(min == 1);
-    CHECK(max == 1);
-    CHECK(res==0);
-}