diff --git a/src/bech32.c b/src/bech32.c
index bfbda6144..8600cea04 100644
--- a/src/bech32.c
+++ b/src/bech32.c
@@ -208,7 +208,7 @@ int wally_addr_segwit_from_bytes(const unsigned char *bytes, size_t bytes_len,
                                  const char *addr_family, uint32_t flags,
                                  char **output)
 {
-    char result[90];
+    char result[90 + 1]; /* Max encoded length plus NUL */
     size_t push_size;
     int ret;
     size_t witver;
diff --git a/src/swig_python/swig.i b/src/swig_python/swig.i
index 039c66292..2b2221cfd 100644
--- a/src/swig_python/swig.i
+++ b/src/swig_python/swig.i
@@ -43,8 +43,10 @@ del swig_import_helper
 #include "../internal.h"
 
 #undef malloc
+#undef calloc
 #undef free
 #define malloc(size) wally_malloc(size)
+#define calloc(n, size) wally_calloc((n) * (size))
 #define free(ptr) wally_free(ptr)
 
 static int check_result(int result)
@@ -182,7 +184,7 @@ static void destroy_words(PyObject *obj) { (void)obj; }
 }
 %typemap(argout) size_t* written {
    Py_DecRef($result);
-   $result = PyInt_FromSize_t(*$1);
+   $result = PyLong_FromSize_t(*$1);
 }
 
 %typemap(in, numinputs=0) uint32_t *value_out (uint32_t val) {
@@ -209,7 +211,7 @@ static void destroy_words(PyObject *obj) { (void)obj; }
 %typemap(argout) char** {
    if (*$1 != NULL) {
        Py_DecRef($result);
-       $result = PyString_FromString(*$1);
+       $result = PyUnicode_FromString(*$1);
        wally_free_string(*$1);
    }
 }
@@ -228,7 +230,7 @@ static void destroy_words(PyObject *obj) { (void)obj; }
        Py_DecRef($result);
        $result = PyList_New($2);
        for (i = 0; i < $2; i++) {
-           PyObject *s = PyString_FromString($1[i]);
+           PyObject *s = PyUnicode_FromString($1[i]);
            PyList_SetItem($result, i, s);
            wally_free_string($1[i]);
        }
diff --git a/src/test/test_bech32.py b/src/test/test_bech32.py
index 2aa77c408..0e51cb529 100755
--- a/src/test/test_bech32.py
+++ b/src/test/test_bech32.py
@@ -20,7 +20,10 @@
     'tb1pqqqqp399et2xygdj5xreqhjjvcmzhxw4aywxecjdzew6hylgvsesf3hn0c':
         ['tb', 1, '5120000000c4a5cad46221b2a187905e5266362b99d5e91c6ce24d165dab93e86433'],
     'bc1p0xlxvlhemja6c4dqv22uapctqupfhlxm9h8z3k2e72q4k9hcz7vqzk5jj0':
-        ['bc', 1, '512079be667ef9dcbbac55a06295ce870b07029bfcdb2dce28d959f2815b16f81798']
+        ['bc', 1, '512079be667ef9dcbbac55a06295ce870b07029bfcdb2dce28d959f2815b16f81798'],
+    # Maximum length (90 character) address: 30 character hrp, 32 byte v0 program
+    'aaaaaaaaaaaaaaaaaaaaaaaaaaaaaa1qqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqq6nf3d':
+        ['a' * 30, 0, '0020' + '00' * 32],
 }
 
 invalid_cases = [