diff --git a/src/test/java/net/kemitix/mon/MaybeTest.java b/src/test/java/net/kemitix/mon/MaybeTest.java
index 61941ee..575826a 100644
--- a/src/test/java/net/kemitix/mon/MaybeTest.java
+++ b/src/test/java/net/kemitix/mon/MaybeTest.java
@@ -51,8 +51,13 @@ public class MaybeTest implements WithAssertions {
     }
 
     @Test
-    public void testHashCode() {
-        assertThat(just(1).hashCode()).isEqualTo(Objects.hashCode(1));
+    public void justHashCode() {
+        assertThat(just(1).hashCode()).isNotEqualTo(just(2).hashCode());
+    }
+
+    @Test
+    public void nothingHashCode() {
+        assertThat(nothing().hashCode()).isEqualTo(maybe(null).hashCode());
     }
 
     @Test
diff --git a/src/test/java/net/kemitix/mon/ResultTest.java b/src/test/java/net/kemitix/mon/ResultTest.java
index 0f28501..5e56fca 100644
--- a/src/test/java/net/kemitix/mon/ResultTest.java
+++ b/src/test/java/net/kemitix/mon/ResultTest.java
@@ -18,6 +18,22 @@ public class ResultTest implements WithAssertions {
         assertThat(Result.ok(1).equals("1")).isFalse();
     }
 
+    @Test
+    public void successHashCode() {
+        assertThat(Result.ok(1).hashCode()).isNotEqualTo(Result.ok(2).hashCode());
+    }
+
+    @Test
+    public void errorHashCode() {
+        // despite having 'equivalent' exceptions, the exceptions are distinct instances, so should be considered unique
+        final RuntimeException exception1 = new RuntimeException("message");
+        final RuntimeException exception2 = new RuntimeException("message");
+        assertThat(exception1.hashCode()).isNotEqualTo(exception2.hashCode());
+        final Result<Object> error1 = Result.error(exception1);
+        final Result<Object> error2 = Result.error(exception2);
+        assertThat(error1.hashCode()).isNotEqualTo(error2.hashCode());
+    }
+
     @Test
     public void createSuccess_isSuccess() {
         //when