diff --git a/picotestify/assert/assert.go b/picotestify/assert/assert.go
index ff68dee..060d451 100644
--- a/picotestify/assert/assert.go
+++ b/picotestify/assert/assert.go
@@ -166,7 +166,11 @@ func ErrorContains(t TestingT, err error, contains string, msgAndArgs ...any) bo
 		return true
 	}
 
-	fail(t, msgAndArgs, "Error %q does not contain %q", err.Error(), contains)
+	if err == nil {
+		fail(t, msgAndArgs, "Expected error containing %q but got nil", contains)
+	} else {
+		fail(t, msgAndArgs, "Error %q does not contain %q", err.Error(), contains)
+	}
 
 	return false
 }
diff --git a/picotestify/assert/assert_test.go b/picotestify/assert/assert_test.go
index 8ed3b58..e496638 100644
--- a/picotestify/assert/assert_test.go
+++ b/picotestify/assert/assert_test.go
@@ -95,6 +95,11 @@ func TestAssert(t *testing.T) {
 			pass: func(t assert.TestingT) { assert.ErrorContains(t, errors.New("test error: check"), "error") },
 			fail: func(t assert.TestingT) { assert.ErrorContains(t, errors.New("test error: check"), "error2") },
 		},
+		{
+			name: "ErrorContains - nil",
+			pass: func(t assert.TestingT) { assert.ErrorContains(t, errors.New("test error: check"), "error") },
+			fail: func(t assert.TestingT) { assert.ErrorContains(t, nil, "error") },
+		},
 		{
 			name: "Empty",
 			pass: func(t assert.TestingT) { assert.Empty(t, []int{}) },