diff --git a/src/test/java/com/h2/Module04_Test.java b/src/test/java/com/h2/Module04_Test.java
index 1320b1b27..fead18b1e 100644
--- a/src/test/java/com/h2/Module04_Test.java
+++ b/src/test/java/com/h2/Module04_Test.java
@@ -10,11 +10,9 @@
 import java.io.ByteArrayOutputStream;
 import java.io.InputStream;
 import java.io.PrintStream;
-import java.lang.reflect.Constructor;
-import java.lang.reflect.Field;
-import java.lang.reflect.InvocationTargetException;
-import java.lang.reflect.Parameter;
+import java.lang.reflect.*;
 import java.util.*;
+import java.util.stream.Collectors;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertTrue;
@@ -133,4 +131,22 @@ public void m4_03_testMortgageConstructorAndCorrectness() throws IllegalAccessEx
         }
 
     }
+
+    @Test
+    public void m4_03_testExistenceOfNumberOfPayments() {
+        final String methodName = "getNumberOfPayments";
+
+        final Optional<Class<?>> maybeMortgageCalculator = getMortgageClass();
+        assertTrue(maybeMortgageCalculator.isPresent(), classToFind + " must exist");
+        final Class<?> mortgageCalculator = maybeMortgageCalculator.get();
+
+        final Method[] methods = mortgageCalculator.getDeclaredMethods();
+        final List<Method> filteredMethod = Arrays.stream(methods).filter(method -> method.getName().equals(methodName)).collect(Collectors.toList());
+
+        assertEquals(1, filteredMethod.size(), classToFind + " should contain a method called '" + methodName + "'");
+
+        final Method sumOfCredits = filteredMethod.get(0);
+        assertTrue(isPrivate(sumOfCredits), methodName + " must be declared as 'private'");
+        assertEquals(int.class, sumOfCredits.getReturnType(), methodName + " method must return a value of type 'int'");
+    }
 }