diff --git a/tests/circuitpython/aes.py b/tests/circuitpython/aes.py
index 40adc020c6..b47c4279d3 100644
--- a/tests/circuitpython/aes.py
+++ b/tests/circuitpython/aes.py
@@ -97,3 +97,47 @@ for i in range(0, len(plaintext), 16):
     cipher.decrypt_into(cyphertext[i : i + 16], output)
     print(str(hexlify(output), ""))
 print()
+
+print("truncated-CTR-1")
+## Truncated CTR test case
+plaintext = unhexlify("6bc1bee22e409f96e93d7e117393172a" "ae2d")
+
+key = unhexlify("2b7e151628aed2a6abf7158809cf4f3c")
+counter = unhexlify("f0f1f2f3f4f5f6f7f8f9fafbfcfdfeff")
+cyphertext = bytearray(len(plaintext))
+cipher = aesio.AES(key, aesio.MODE_CTR, IV=counter)
+for i in range(0, len(plaintext), 16):
+    output = memoryview(cyphertext)[i : i + 16]
+    cipher.encrypt_into(plaintext[i : i + 16], output)
+    print(str(hexlify(output), ""))
+print()
+
+plaintext = bytearray(len(plaintext))
+cipher = aesio.AES(key, aesio.MODE_CTR, IV=counter)
+for i in range(0, len(plaintext), 16):
+    output = memoryview(plaintext)[i : i + 16]
+    cipher.decrypt_into(cyphertext[i : i + 16], output)
+    print(str(hexlify(output), ""))
+print()
+
+print("truncated-CTR-2")
+## Truncated CTR test case #2
+plaintext = unhexlify("6bc1bee22e409f96e93d7e117393172a" "ae")
+
+key = unhexlify("2b7e151628aed2a6abf7158809cf4f3c")
+counter = unhexlify("f0f1f2f3f4f5f6f7f8f9fafbfcfdfeff")
+cyphertext = bytearray(len(plaintext))
+cipher = aesio.AES(key, aesio.MODE_CTR, IV=counter)
+cipher.encrypt_into(plaintext, cyphertext)
+for i in range(0, len(plaintext), 16):
+    output = memoryview(cyphertext)[i : i + 16]
+    print(str(hexlify(output), ""))
+print()
+
+plaintext = bytearray(len(plaintext))
+cipher = aesio.AES(key, aesio.MODE_CTR, IV=counter)
+cipher.decrypt_into(cyphertext, plaintext)
+for i in range(0, len(plaintext), 16):
+    output = memoryview(plaintext)[i : i + 16]
+    print(str(hexlify(output), ""))
+print()
diff --git a/tests/circuitpython/aes.py.exp b/tests/circuitpython/aes.py.exp
index da0f8c29b1..17a2bfe12a 100644
--- a/tests/circuitpython/aes.py.exp
+++ b/tests/circuitpython/aes.py.exp
@@ -34,3 +34,17 @@ ae2d8a571e03ac9c9eb76fac45af8e51
 30c81c46a35ce411e5fbc1191a0a52ef
 f69f2445df4f9b17ad2b417be66c3710
 
+truncated-CTR-1
+874d6191b620e3261bef6864990db6ce
+9806
+
+6bc1bee22e409f96e93d7e117393172a
+ae2d
+
+truncated-CTR-2
+874d6191b620e3261bef6864990db6ce
+98
+
+6bc1bee22e409f96e93d7e117393172a
+ae
+