diff --git a/sumatra/projects.py b/sumatra/projects.py
index 36e4b6c9..240bab1f 100644
--- a/sumatra/projects.py
+++ b/sumatra/projects.py
@@ -359,7 +359,7 @@ def add_comment(self, label, comment, replace=False):
             record = self.record_store.get(self.name, label)
         except Exception as e:
             raise Exception("%s. label=<%s>" % (e, label))
-        if replace or record.outcome is "":
+        if replace or record.outcome == "":
             record.outcome = comment
         else:
             record.outcome = record.outcome + "\n" + comment
diff --git a/sumatra/versioncontrol/_git.py b/sumatra/versioncontrol/_git.py
index 74c7b447..2db9d501 100644
--- a/sumatra/versioncontrol/_git.py
+++ b/sumatra/versioncontrol/_git.py
@@ -84,7 +84,7 @@ def current_version(self):
 
     def use_version(self, version):
         logger.debug("Using git version: %s" % version)
-        if version is not 'master':
+        if version != 'master':
             assert not self.has_changed()
         g = git.Git(self.path)
         g.checkout(version)