diff --git a/.travis.yml b/.travis.yml
index 3e2f23635..78362e588 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -29,7 +29,8 @@ addons:
     - libudev-dev
 
 install:
-    - pip install ed25519 pyblake2
+    - pip3 install scons
+    - pip3 install ed25519 pyblake2
     - pip3 install flake8
     - pip3 install pytest
     - pip3 install ecdsa mnemonic protobuf requests
diff --git a/src/trezor/messages/EncryptMessage.py b/src/trezor/messages/EncryptMessage.py
index 6ed3d54b6..b0177f5c3 100644
--- a/src/trezor/messages/EncryptMessage.py
+++ b/src/trezor/messages/EncryptMessage.py
@@ -8,6 +8,6 @@ class EncryptMessage(p.MessageType):
         2: ('message', p.BytesType, 0),
         3: ('display_only', p.BoolType, 0),
         4: ('address_n', p.UVarintType, p.FLAG_REPEATED),
-        5: ('coin_name', p.UnicodeType, 0),  # default=u'Bitcoin'
+        5: ('coin_name', p.UnicodeType, 0),  # default='Bitcoin'
     }
     MESSAGE_WIRE_TYPE = 49
diff --git a/src/trezor/messages/EstimateTxSize.py b/src/trezor/messages/EstimateTxSize.py
index 5f24fe901..9a9342b34 100644
--- a/src/trezor/messages/EstimateTxSize.py
+++ b/src/trezor/messages/EstimateTxSize.py
@@ -6,6 +6,6 @@ class EstimateTxSize(p.MessageType):
     FIELDS = {
         1: ('outputs_count', p.UVarintType, 0),  # required
         2: ('inputs_count', p.UVarintType, 0),  # required
-        3: ('coin_name', p.UnicodeType, 0),  # default=u'Bitcoin'
+        3: ('coin_name', p.UnicodeType, 0),  # default='Bitcoin'
     }
     MESSAGE_WIRE_TYPE = 43
diff --git a/src/trezor/messages/GetAddress.py b/src/trezor/messages/GetAddress.py
index 175a33153..ad08d4314 100644
--- a/src/trezor/messages/GetAddress.py
+++ b/src/trezor/messages/GetAddress.py
@@ -6,7 +6,7 @@ from .MultisigRedeemScriptType import MultisigRedeemScriptType
 class GetAddress(p.MessageType):
     FIELDS = {
         1: ('address_n', p.UVarintType, p.FLAG_REPEATED),
-        2: ('coin_name', p.UnicodeType, 0),  # default=u'Bitcoin'
+        2: ('coin_name', p.UnicodeType, 0),  # default='Bitcoin'
         3: ('show_display', p.BoolType, 0),
         4: ('multisig', MultisigRedeemScriptType, 0),
         5: ('script_type', p.UVarintType, 0),  # default=0
diff --git a/src/trezor/messages/GetPublicKey.py b/src/trezor/messages/GetPublicKey.py
index 0bb964012..b16ac25a3 100644
--- a/src/trezor/messages/GetPublicKey.py
+++ b/src/trezor/messages/GetPublicKey.py
@@ -7,6 +7,6 @@ class GetPublicKey(p.MessageType):
         1: ('address_n', p.UVarintType, p.FLAG_REPEATED),
         2: ('ecdsa_curve_name', p.UnicodeType, 0),
         3: ('show_display', p.BoolType, 0),
-        4: ('coin_name', p.UnicodeType, 0),  # default=u'Bitcoin'
+        4: ('coin_name', p.UnicodeType, 0),  # default='Bitcoin'
     }
     MESSAGE_WIRE_TYPE = 11
diff --git a/src/trezor/messages/LoadDevice.py b/src/trezor/messages/LoadDevice.py
index 5ccbdd201..262488414 100644
--- a/src/trezor/messages/LoadDevice.py
+++ b/src/trezor/messages/LoadDevice.py
@@ -9,7 +9,7 @@ class LoadDevice(p.MessageType):
         2: ('node', HDNodeType, 0),
         3: ('pin', p.UnicodeType, 0),
         4: ('passphrase_protection', p.BoolType, 0),
-        5: ('language', p.UnicodeType, 0),  # default=u'english'
+        5: ('language', p.UnicodeType, 0),  # default='english'
         6: ('label', p.UnicodeType, 0),
         7: ('skip_checksum', p.BoolType, 0),
         8: ('u2f_counter', p.UVarintType, 0),
diff --git a/src/trezor/messages/RecoveryDevice.py b/src/trezor/messages/RecoveryDevice.py
index b32e5fc30..d6c21aa58 100644
--- a/src/trezor/messages/RecoveryDevice.py
+++ b/src/trezor/messages/RecoveryDevice.py
@@ -7,7 +7,7 @@ class RecoveryDevice(p.MessageType):
         1: ('word_count', p.UVarintType, 0),
         2: ('passphrase_protection', p.BoolType, 0),
         3: ('pin_protection', p.BoolType, 0),
-        4: ('language', p.UnicodeType, 0),  # default=u'english'
+        4: ('language', p.UnicodeType, 0),  # default='english'
         5: ('label', p.UnicodeType, 0),
         6: ('enforce_wordlist', p.BoolType, 0),
         8: ('type', p.UVarintType, 0),
diff --git a/src/trezor/messages/ResetDevice.py b/src/trezor/messages/ResetDevice.py
index 25afe5cc3..6ea628abd 100644
--- a/src/trezor/messages/ResetDevice.py
+++ b/src/trezor/messages/ResetDevice.py
@@ -8,7 +8,7 @@ class ResetDevice(p.MessageType):
         2: ('strength', p.UVarintType, 0),  # default=256
         3: ('passphrase_protection', p.BoolType, 0),
         4: ('pin_protection', p.BoolType, 0),
-        5: ('language', p.UnicodeType, 0),  # default=u'english'
+        5: ('language', p.UnicodeType, 0),  # default='english'
         6: ('label', p.UnicodeType, 0),
         7: ('u2f_counter', p.UVarintType, 0),
         8: ('skip_backup', p.BoolType, 0),
diff --git a/src/trezor/messages/SignMessage.py b/src/trezor/messages/SignMessage.py
index 7bd83ccc1..9f238882d 100644
--- a/src/trezor/messages/SignMessage.py
+++ b/src/trezor/messages/SignMessage.py
@@ -6,7 +6,7 @@ class SignMessage(p.MessageType):
     FIELDS = {
         1: ('address_n', p.UVarintType, p.FLAG_REPEATED),
         2: ('message', p.BytesType, 0),  # required
-        3: ('coin_name', p.UnicodeType, 0),  # default=u'Bitcoin'
+        3: ('coin_name', p.UnicodeType, 0),  # default='Bitcoin'
         4: ('script_type', p.UVarintType, 0),  # default=0
     }
     MESSAGE_WIRE_TYPE = 38
diff --git a/src/trezor/messages/SignTx.py b/src/trezor/messages/SignTx.py
index 45f2f2aab..431325400 100644
--- a/src/trezor/messages/SignTx.py
+++ b/src/trezor/messages/SignTx.py
@@ -6,7 +6,7 @@ class SignTx(p.MessageType):
     FIELDS = {
         1: ('outputs_count', p.UVarintType, 0),  # required
         2: ('inputs_count', p.UVarintType, 0),  # required
-        3: ('coin_name', p.UnicodeType, 0),  # default=u'Bitcoin'
+        3: ('coin_name', p.UnicodeType, 0),  # default='Bitcoin'
         4: ('version', p.UVarintType, 0),  # default=1
         5: ('lock_time', p.UVarintType, 0),  # default=0
     }
diff --git a/src/trezor/messages/SimpleSignTx.py b/src/trezor/messages/SimpleSignTx.py
index 920c9f634..7283256d5 100644
--- a/src/trezor/messages/SimpleSignTx.py
+++ b/src/trezor/messages/SimpleSignTx.py
@@ -10,7 +10,7 @@ class SimpleSignTx(p.MessageType):
         1: ('inputs', TxInputType, p.FLAG_REPEATED),
         2: ('outputs', TxOutputType, p.FLAG_REPEATED),
         3: ('transactions', TransactionType, p.FLAG_REPEATED),
-        4: ('coin_name', p.UnicodeType, 0),  # default=u'Bitcoin'
+        4: ('coin_name', p.UnicodeType, 0),  # default='Bitcoin'
         5: ('version', p.UVarintType, 0),  # default=1
         6: ('lock_time', p.UVarintType, 0),  # default=0
     }
diff --git a/src/trezor/messages/VerifyMessage.py b/src/trezor/messages/VerifyMessage.py
index 9cc4cb1dc..88428aeeb 100644
--- a/src/trezor/messages/VerifyMessage.py
+++ b/src/trezor/messages/VerifyMessage.py
@@ -7,6 +7,6 @@ class VerifyMessage(p.MessageType):
         1: ('address', p.UnicodeType, 0),
         2: ('signature', p.BytesType, 0),
         3: ('message', p.BytesType, 0),
-        4: ('coin_name', p.UnicodeType, 0),  # default=u'Bitcoin'
+        4: ('coin_name', p.UnicodeType, 0),  # default='Bitcoin'
     }
     MESSAGE_WIRE_TYPE = 39
diff --git a/tools/binctl b/tools/binctl
index 8c1de50d5..05e88819f 100755
--- a/tools/binctl
+++ b/tools/binctl
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 
 from __future__ import print_function
 
diff --git a/tools/build_protobuf b/tools/build_protobuf
index c5d8eba7d..0d306270f 100755
--- a/tools/build_protobuf
+++ b/tools/build_protobuf
@@ -1,7 +1,7 @@
 #!/bin/bash
 CURDIR=$(pwd)
 mkdir -p $CURDIR/pb2/
-echo > $CURDIR/pb2/__init__.py
+touch $CURDIR/pb2/__init__.py
 
 mkdir -p ../src/trezor/messages
 
@@ -17,6 +17,10 @@ for i in types messages storage ; do
     protoc --python_out=$CURDIR/pb2/ -I/usr/include -I. $i.proto
 done
 
+# hack to make output python 3 compatible
+sed -i 's/^import types_pb2/from . import types_pb2/g' $CURDIR/pb2/messages_pb2.py
+sed -i 's/^import types_pb2/from . import types_pb2/g' $CURDIR/pb2/storage_pb2.py
+
 for i in types messages storage ; do
     # Convert google protobuf library to trezor's internal format
     cd $CURDIR
diff --git a/tools/pb2py b/tools/pb2py
index c0546829d..bfeb15a4e 100755
--- a/tools/pb2py
+++ b/tools/pb2py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 # Converts Google's protobuf python definitions of TREZOR wire messages
 # to plain-python objects as used in TREZOR Core and python-trezor