diff --git a/capa/features/extractors/viv/__init__.py b/capa/features/extractors/viv/__init__.py
index c6511215..47581236 100644
--- a/capa/features/extractors/viv/__init__.py
+++ b/capa/features/extractors/viv/__init__.py
@@ -8,11 +8,7 @@
 
 import types
 
-import file
-import insn
-import function
 import viv_utils
-import basicblock
 
 import capa.features.extractors
 import capa.features.extractors.viv.file
@@ -42,7 +38,7 @@ def add_va_int_cast(o):
     this bit of skullduggery lets use cast viv-utils objects as ints.
     the correct way of doing this is to update viv-utils (or subclass the objects here).
     """
-    setattr(o, "__int__", types.MethodType(get_va, o, type(o)))
+    setattr(o, "__int__", types.MethodType(get_va, o))
     return o
 
 
diff --git a/capa/features/extractors/viv/basicblock.py b/capa/features/extractors/viv/basicblock.py
index 69ae94f6..76ffefe6 100644
--- a/capa/features/extractors/viv/basicblock.py
+++ b/capa/features/extractors/viv/basicblock.py
@@ -125,11 +125,16 @@ def get_printable_len(oper):
 
 
 def is_printable_ascii(chars):
-    return all(ord(c) < 127 and c in string.printable for c in chars)
+    try:
+        chars_str = chars.decode("ascii")
+    except UnicodeDecodeError:
+        return False
+    else:
+        return all(c in string.printable for c in chars_str)
 
 
 def is_printable_utf16le(chars):
-    if all(c == "\x00" for c in chars[1::2]):
+    if all(c == b"\x00" for c in chars[1::2]):
         return is_printable_ascii(chars[::2])
 
 
diff --git a/capa/main.py b/capa/main.py
index 27d5a9c3..2bb14ade 100644
--- a/capa/main.py
+++ b/capa/main.py
@@ -32,7 +32,7 @@ import capa.features.extractors
 from capa.helpers import oint, get_file_taste
 
 RULES_PATH_DEFAULT_STRING = "(embedded rules)"
-SUPPORTED_FILE_MAGIC = set(["MZ"])
+SUPPORTED_FILE_MAGIC = set([b"MZ"])
 
 
 logger = logging.getLogger("capa")
@@ -304,19 +304,33 @@ class UnsupportedRuntimeError(RuntimeError):
 
 
 def get_extractor_py3(path, format, disable_progress=False):
-    from smda.SmdaConfig import SmdaConfig
-    from smda.Disassembler import Disassembler
+    if False:
+        from smda.SmdaConfig import SmdaConfig
+        from smda.Disassembler import Disassembler
 
-    import capa.features.extractors.smda
+        import capa.features.extractors.smda
 
-    smda_report = None
-    with halo.Halo(text="analyzing program", spinner="simpleDots", stream=sys.stderr, enabled=not disable_progress):
-        config = SmdaConfig()
-        config.STORE_BUFFER = True
-        smda_disasm = Disassembler(config)
-        smda_report = smda_disasm.disassembleFile(path)
+        smda_report = None
+        with halo.Halo(text="analyzing program", spinner="simpleDots", stream=sys.stderr, enabled=not disable_progress):
+            config = SmdaConfig()
+            config.STORE_BUFFER = True
+            smda_disasm = Disassembler(config)
+            smda_report = smda_disasm.disassembleFile(path)
 
-    return capa.features.extractors.smda.SmdaFeatureExtractor(smda_report, path)
+        return capa.features.extractors.smda.SmdaFeatureExtractor(smda_report, path)
+    else:
+        import capa.features.extractors.viv
+
+        with halo.Halo(text="analyzing program", spinner="simpleDots", stream=sys.stderr, enabled=not disable_progress):
+            vw = get_workspace(path, format, should_save=False)
+
+            try:
+                vw.saveWorkspace()
+            except IOError:
+                # see #168 for discussion around how to handle non-writable directories
+                logger.info("source directory is not writable, won't save intermediate workspace")
+
+        return capa.features.extractors.viv.VivisectFeatureExtractor(vw, path)
 
 
 def get_extractor(path, format, disable_progress=False):
diff --git a/setup.py b/setup.py
index 4caaa749..c739f1b7 100644
--- a/setup.py
+++ b/setup.py
@@ -27,6 +27,8 @@ if sys.version_info >= (3, 0):
     # py3
     requirements.append("halo")
     requirements.append("networkx")
+    requirements.append("vivisect @ git+https://github.com/Ana06/vivisect@py-3#egg=vivisect")
+    requirements.append("viv-utils==0.3.19")
     requirements.append("smda==1.5.13")
 else:
     # py2