diff --git a/test/unit/test_tools.py b/test/unit/test_tools.py
new file mode 100644
index 0000000..ba5b834
--- /dev/null
+++ b/test/unit/test_tools.py
@@ -0,0 +1,16 @@
+from pisa.tools import check_txid_format
+from pisa import logging
+
+logging.getLogger().disabled = True
+
+
+def test_check_txid_format():
+    assert(check_txid_format(None) is False)
+    assert(check_txid_format("") is False)
+    assert(check_txid_format(0x0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef) is False)  # wrong type
+    assert(check_txid_format("0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef") is True)  # lowercase
+    assert(check_txid_format("0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF") is True)  # uppercase
+    assert(check_txid_format("0123456789abcdef0123456789ABCDEF0123456789abcdef0123456789ABCDEF") is True)  # mixed case
+    assert(check_txid_format("0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdf") is False)  # too short
+    assert(check_txid_format("0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef0") is False)  # too long
+    assert(check_txid_format("g123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef") is False)  # non-hex