diff --git a/exercises/rna-transcription/rna_transcription_test.py b/exercises/rna-transcription/rna_transcription_test.py
index 663416b1088..b69ba0f2338 100644
--- a/exercises/rna-transcription/rna_transcription_test.py
+++ b/exercises/rna-transcription/rna_transcription_test.py
@@ -25,6 +25,18 @@ def test_transcribes_adenine_to_uracil(self):
     def test_transcribes_all_occurrences(self):
         self.assertEqual(to_rna('ACGTGGTCTTAA'), 'UGCACCAGAAUU')
 
+    def test_invalid_nucleotide(self):
+        with self.assertRaises(ValueError):
+            to_rna('X')
+
+    def test_invalid_strand(self):
+        with self.assertRaises(ValueError):
+            to_rna('XYYP')
+
+    def test_partially_invalid_strand(self):
+        with self.assertRaises(ValueError):
+            to_rna('ACGTGGXYTCTTAAYP')
+
 
 if __name__ == '__main__':
     unittest.main()