diff --git a/src/rez/cli/release.py b/src/rez/cli/release.py
index f04282a15..92436edc8 100644
--- a/src/rez/cli/release.py
+++ b/src/rez/cli/release.py
@@ -82,7 +82,7 @@ def command(opts, parser, extra_arg_groups=None):
     if config.prompt_release_message and not release_msg and not opts.no_message:
         from hashlib import sha1
 
-        h = sha1(working_dir).hexdigest()
+        h = sha1(working_dir.encode("utf8")).hexdigest()
         filename = "rez-release-message-%s.txt" % h
         filepath = os.path.join(config.tmpdir, filename)
 
diff --git a/src/rez/resolver.py b/src/rez/resolver.py
index f72b918d6..30b92ceab 100644
--- a/src/rez/resolver.py
+++ b/src/rez/resolver.py
@@ -69,7 +69,7 @@ def __init__(self, context, package_requests, package_paths, package_filter=None
         # store hash of package orderers. This is used in the memcached key
         if package_orderers:
             sha1s = ''.join(x.sha1 for x in package_orderers)
-            self.package_orderers_hash = sha1(sha1s).hexdigest()
+            self.package_orderers_hash = sha1(sha1s.encode("utf8")).hexdigest()
         else:
             self.package_orderers_hash = ''
 
diff --git a/src/rez/utils/sourcecode.py b/src/rez/utils/sourcecode.py
index 508f6a1d6..2906660ab 100644
--- a/src/rez/utils/sourcecode.py
+++ b/src/rez/utils/sourcecode.py
@@ -312,7 +312,7 @@ def load_module(self, name, package):
             if not os.path.exists(filepath):
                 return None
 
-            with open(filepath) as f:
+            with open(filepath, "rb") as f:
                 txt = f.read().strip()
 
             hash_str = sha1(txt).hexdigest()