diff --git a/data_structures/test_stack.cpp b/data_structures/test_stack.cpp
index 965dab017..9a7cc18ff 100644
--- a/data_structures/test_stack.cpp
+++ b/data_structures/test_stack.cpp
@@ -10,10 +10,11 @@ int main() {
     std::cout
         << "---------------------- Test isEmptyStack ----------------------"
         << std::endl;
-    if (stk.isEmptyStack())
+    if (stk.isEmptyStack()) {
         std::cout << "PASS" << std::endl;
-    else
+    } else {
         std::cout << "FAIL" << std::endl;
+    }
     std::cout << "---------------------- Test push ----------------------"
               << std::endl;
     std::cout << "After pushing 10 20 30 40 into stack: " << std::endl;
@@ -25,10 +26,11 @@ int main() {
     std::cout << "---------------------- Test top ----------------------"
               << std::endl;
     int value = stk.top();
-    if (value == 40)
+    if (value == 40) {
         std::cout << "PASS" << std::endl;
-    else
+    } else {
         std::cout << "FAIL" << std::endl;
+    }
     std::cout << "---------------------- Test pop ----------------------"
               << std::endl;
     stk.display();
diff --git a/data_structures/test_stack_students.cpp b/data_structures/test_stack_students.cpp
index b28055be3..b22e26b5c 100644
--- a/data_structures/test_stack_students.cpp
+++ b/data_structures/test_stack_students.cpp
@@ -15,10 +15,11 @@
 #include <string>
 
 #include "./stack.hpp"
+#include "math.h"
 
 int main(int argc, char* argv[]) {
-    double GPA;
-    double highestGPA;
+    double GPA = NAN;
+    double highestGPA = NAN;
     std::string name;
 
     assert(argc == 2);