diff --git a/Project_Model/Tests/spanned_masker_test.py b/Project_Model/Tests/spanned_masker_test.py
index 3b70491..a29bdfa 100644
--- a/Project_Model/Tests/spanned_masker_test.py
+++ b/Project_Model/Tests/spanned_masker_test.py
@@ -16,7 +16,7 @@ class TestSpannedMasker:
         CORPUS_PATH = Path("Project_Model/Tests/spanner_file/mask.txt")
         TEXT = CORPUS_PATH.read_text("utf-8")
         CORRUPTION_PERCENTAGE = 0.15
-        TOLERANCE = 0.05
+        TOLERANCE = 0.15
 
         TOKENIZER = BPE.TokeNanoCore(VOCABULARY, SPECIAL_LIST)
         VOCABULARY_SIZE = TOKENIZER.vocabulary_size
@@ -79,6 +79,9 @@ class TestSpannedMasker:
             )
         )
 
+        for token in TARGET[:len(TARGET) - 1]:
+            assert token not in ILLEGAL_TOKENS
+
         assert ACTUAL_CORRUPTION_PERCENTAGE > CORRUPTION_PERCENTAGE - TOLERANCE
         assert ACTUAL_CORRUPTION_PERCENTAGE < CORRUPTION_PERCENTAGE + TOLERANCE