diff --git a/src/apps/common/signverify.py b/src/apps/common/signverify.py
index 7b5c6b86b..f50379b3a 100644
--- a/src/apps/common/signverify.py
+++ b/src/apps/common/signverify.py
@@ -1,6 +1,7 @@
+from ubinascii import hexlify
 from micropython import const
 from trezor.crypto.hashlib import sha256
-from trezor.utils import chunks
+from trezor.utils import chunks, split_words
 from apps.common.hash_writer import HashWriter
 from apps.wallet.sign_tx.signing import write_varint
 
@@ -15,12 +16,10 @@ def message_digest(coin, message):
 
 
 def split_message(message):
-    chars_per_line = const(18)
-    message = stringify_message(message)
-    lines = chunks(message, chars_per_line)
+    try:
+        m = bytes(message).decode()
+        lines = split_words(m, 18)
+    except UnicodeError:
+        m = hexlify(message)
+        lines = chunks(m, 16)
     return lines
-
-
-def stringify_message(message):
-    # TODO: account for invalid UTF-8 sequences
-    return str(message, 'utf-8')
diff --git a/src/apps/wallet/sign_message.py b/src/apps/wallet/sign_message.py
index 63eb14d7c..b1395ad09 100644
--- a/src/apps/wallet/sign_message.py
+++ b/src/apps/wallet/sign_message.py
@@ -1,5 +1,8 @@
 from trezor import ui
+from trezor.wire import FailureError
 from trezor.crypto.curve import secp256k1
+from trezor.messages.InputScriptType import SPENDADDRESS
+from trezor.messages.FailureType import ProcessError
 from trezor.messages.MessageSignature import MessageSignature
 from trezor.ui.text import Text
 from apps.common import coins, seed
@@ -11,8 +14,12 @@ async def sign_message(ctx, msg):
     message = msg.message
     address_n = msg.address_n
     coin_name = msg.coin_name or 'Bitcoin'
+    script_type = msg.script_type or 0
     coin = coins.by_name(coin_name)
 
+    if script_type != SPENDADDRESS:
+        raise FailureError(ProcessError, 'Unsupported script type')
+
     await confirm_sign_message(ctx, message)
 
     node = await seed.derive_node(ctx, address_n)
diff --git a/src/trezor/utils.py b/src/trezor/utils.py
index faeb49226..931b031e4 100644
--- a/src/trezor/utils.py
+++ b/src/trezor/utils.py
@@ -18,14 +18,30 @@ def unimport(genfunc):
     return inner
 
 
+def ensure(cond):
+    if not cond:
+        raise AssertionError()
+
+
 def chunks(items, size):
     for i in range(0, len(items), size):
         yield items[i:i + size]
 
 
-def ensure(cond):
-    if not cond:
-        raise AssertionError()
+def split_words(sentence, width, metric=len):
+    line = ''
+    for c in sentence:
+        line += c
+        if metric(line) >= width:
+            c = line[-1]
+            if c == ' ':
+                yield line
+                line = ''
+            else:
+                yield line[:-1] + '-'
+                line = c
+    if line != '':
+        yield line
 
 
 def format_amount(amount, decimals):