diff --git a/src/lint/renderer/ArcanistConsoleLintRenderer.php b/src/lint/renderer/ArcanistConsoleLintRenderer.php
--- a/src/lint/renderer/ArcanistConsoleLintRenderer.php
+++ b/src/lint/renderer/ArcanistConsoleLintRenderer.php
@@ -119,6 +119,9 @@
 
     $old = $data;
     $old_lines = phutil_split_lines($old);
+    if ($original == null) {
+      $original = '';
+    }
     $old_impact = substr_count($original, "\n") + 1;
     $start = $line;
 
diff --git a/src/unit/renderer/ArcanistUnitConsoleRenderer.php b/src/unit/renderer/ArcanistUnitConsoleRenderer.php
--- a/src/unit/renderer/ArcanistUnitConsoleRenderer.php
+++ b/src/unit/renderer/ArcanistUnitConsoleRenderer.php
@@ -12,6 +12,9 @@
 
     $test_name = $result->getName();
     $test_namespace = $result->getNamespace();
+    if ($test_namespace == null) {
+      $test_namespace = '';
+    }
     if (strlen($test_namespace)) {
       $test_name = $test_namespace.'::'.$test_name;
     }
diff --git a/src/workflow/ArcanistWorkflow.php b/src/workflow/ArcanistWorkflow.php
--- a/src/workflow/ArcanistWorkflow.php
+++ b/src/workflow/ArcanistWorkflow.php
@@ -199,6 +199,9 @@
     $phutil_workflow->setSynopsis($synopses);
 
     $help = $this->getCommandHelp();
+    if ($help == null) {
+      $help = '';
+    }
     if (strlen($help)) {
       $phutil_workflow->setHelp($help);
     }
@@ -480,6 +483,9 @@
       // token-based authentication. Use that instead of all the certificate
       // stuff.
       $token = idx($credentials, 'token');
+      if ($token == null) {
+        $token = '';
+      }
       if (strlen($token)) {
         $conduit = $this->getConduit();