diff --git a/CHANGES.md b/CHANGES.md
index d5f9bdd64..ec09666dc 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -4,6 +4,7 @@
 
 ### Fixed
 - internal: De-optimize some memcpy calls on x86 to prevent leaks via extended registers.
+- bech32: Fix size when encoding a maximum length (90 character) segwit address.
 - descriptor: Require base miniscript expressions for sh()/wsh().
 - descriptor: Reject nested expressions with unconsumed trailing input.
 
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/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 = [