diff --git a/tests/extmod/ubinascii_a2b_base64.py b/tests/extmod/ubinascii_a2b_base64.py
index 25986b7c0a..97c4519508 100644
--- a/tests/extmod/ubinascii_a2b_base64.py
+++ b/tests/extmod/ubinascii_a2b_base64.py
@@ -14,6 +14,7 @@ print(binascii.a2b_base64(b'Zm9vYmFy'))
 print(binascii.a2b_base64(b'AAECAwQFBgc='))
 print(binascii.a2b_base64(b'CAkKCwwNDg8='))
 print(binascii.a2b_base64(b'f4D/'))
+print(binascii.a2b_base64(b'f4D+')) # convert '+'
 print(binascii.a2b_base64(b'MTIzNEFCQ0RhYmNk'))
 
 try:
diff --git a/tests/extmod/ubinascii_b2a_base64.py b/tests/extmod/ubinascii_b2a_base64.py
index 343c28da22..fdcaf32dd8 100644
--- a/tests/extmod/ubinascii_b2a_base64.py
+++ b/tests/extmod/ubinascii_b2a_base64.py
@@ -15,3 +15,4 @@ print(binascii.b2a_base64(b'\x00\x01\x02\x03\x04\x05\x06\x07'))
 print(binascii.b2a_base64(b'\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f'))
 print(binascii.b2a_base64(b'\x7f\x80\xff'))
 print(binascii.b2a_base64(b'1234ABCDabcd'))
+print(binascii.b2a_base64(b'\x00\x00>')) # convert into '+'
diff --git a/tests/extmod/ubinascii_micropython.py b/tests/extmod/ubinascii_micropython.py
new file mode 100644
index 0000000000..d68da3205d
--- /dev/null
+++ b/tests/extmod/ubinascii_micropython.py
@@ -0,0 +1,8 @@
+try:
+    import ubinascii as binascii
+except ImportError:
+    import binascii
+
+# two arguments supported in uPy but not CPython
+a = binascii.hexlify(b'123', ':')
+print(a)
diff --git a/tests/extmod/ubinascii_micropython.py.exp b/tests/extmod/ubinascii_micropython.py.exp
new file mode 100644
index 0000000000..0ae3d768ef
--- /dev/null
+++ b/tests/extmod/ubinascii_micropython.py.exp
@@ -0,0 +1 @@
+b'31:32:33'
diff --git a/tests/extmod/ubinascii_unhexlify.py b/tests/extmod/ubinascii_unhexlify.py
index 1ec6972c5b..99c2c0208d 100644
--- a/tests/extmod/ubinascii_unhexlify.py
+++ b/tests/extmod/ubinascii_unhexlify.py
@@ -7,3 +7,13 @@ print(binascii.unhexlify(b'0001020304050607'))
 print(binascii.unhexlify(b'08090a0b0c0d0e0f'))
 print(binascii.unhexlify(b'7f80ff'))
 print(binascii.unhexlify(b'313233344142434461626364'))
+
+try:
+    a = binascii.unhexlify(b'0') # odd buffer length
+except ValueError:
+    print('ValueError')
+
+try:
+    a = binascii.unhexlify(b'gg') # digit not hex
+except ValueError:
+    print('ValueError')