diff --git a/src/applications/config/check/PhabricatorPHPPreflightSetupCheck.php b/src/applications/config/check/PhabricatorPHPPreflightSetupCheck.php
index 09b00bc991..c780f8b959 100644
--- a/src/applications/config/check/PhabricatorPHPPreflightSetupCheck.php
+++ b/src/applications/config/check/PhabricatorPHPPreflightSetupCheck.php
@@ -84,7 +84,7 @@ final class PhabricatorPHPPreflightSetupCheck extends PhabricatorSetupCheck {
     }
 
     $open_basedir = ini_get('open_basedir');
-    if (strlen($open_basedir)) {
+    if ($open_basedir && strlen($open_basedir)) {
       // If `open_basedir` is set, just fatal. It's technically possible for
       // us to run with certain values of `open_basedir`, but: we can only
       // raise fatal errors from preflight steps, so we'd have to do this check
diff --git a/src/applications/config/view/PhabricatorSetupIssueView.php b/src/applications/config/view/PhabricatorSetupIssueView.php
index 92c97af5d0..06a1e13c87 100644
--- a/src/applications/config/view/PhabricatorSetupIssueView.php
+++ b/src/applications/config/view/PhabricatorSetupIssueView.php
@@ -372,14 +372,14 @@ final class PhabricatorSetupIssueView extends AphrontView {
     $matches = null;
 
     $ini_loc = null;
-    if (preg_match($rex, $phpinfo, $matches)) {
+    if ($phpinfo && preg_match($rex, $phpinfo, $matches)) {
       $ini_loc = trim($matches[1]);
     }
 
     $rex = '@Additional \.ini files parsed\s*</td><td class="v">(.*?)</td>@i';
 
     $more_loc = array();
-    if (preg_match($rex, $phpinfo, $matches)) {
+    if ($phpinfo && preg_match($rex, $phpinfo, $matches)) {
       $more_loc = trim($matches[1]);
       if ($more_loc == '(none)') {
         $more_loc = array();
diff --git a/src/applications/differential/storage/DifferentialHunk.php b/src/applications/differential/storage/DifferentialHunk.php
index 891fac745a..24730d3abd 100644
--- a/src/applications/differential/storage/DifferentialHunk.php
+++ b/src/applications/differential/storage/DifferentialHunk.php
@@ -225,7 +225,7 @@ final class DifferentialHunk
       }
 
       if ($line[0] == '\\') {
-        if ($use_next_newline) {
+        if ($use_next_newline && $results) {
           $results[last_key($results)] = rtrim(end($results), "\n");
         }
       } else if (empty($include_map[$line[0]])) {
diff --git a/src/applications/diffusion/engine/DiffusionCommitHookEngine.php b/src/applications/diffusion/engine/DiffusionCommitHookEngine.php
index 9f4b1cab2d..d1ead81a4a 100644
--- a/src/applications/diffusion/engine/DiffusionCommitHookEngine.php
+++ b/src/applications/diffusion/engine/DiffusionCommitHookEngine.php
@@ -982,12 +982,12 @@ final class DiffusionCommitHookEngine extends Phobject {
     $key_name = getenv('HG_KEY');
 
     $key_old = getenv('HG_OLD');
-    if (!strlen($key_old)) {
+    if (!$key_old || !strlen($key_old)) {
       $key_old = null;
     }
 
     $key_new = getenv('HG_NEW');
-    if (!strlen($key_new)) {
+    if (!$key_new || !strlen($key_new)) {
       $key_new = null;
     }
 
diff --git a/src/applications/diviner/workflow/DivinerGenerateWorkflow.php b/src/applications/diviner/workflow/DivinerGenerateWorkflow.php
index 69d6a78c2d..57cfe40642 100644
--- a/src/applications/diviner/workflow/DivinerGenerateWorkflow.php
+++ b/src/applications/diviner/workflow/DivinerGenerateWorkflow.php
@@ -55,11 +55,14 @@ final class DivinerGenerateWorkflow extends DivinerWorkflow {
     } else {
       $cwd = getcwd();
       $this->log(pht('FINDING DOCUMENTATION BOOKS'));
+      $books = array();
 
-      $books = id(new FileFinder($cwd))
-        ->withType('f')
-        ->withSuffix('book')
-        ->find();
+      if ($cwd) {
+        $books = id(new FileFinder($cwd))
+          ->withType('f')
+          ->withSuffix('book')
+          ->find();
+      }
 
       if (!$books) {
         throw new PhutilArgumentUsageException(
diff --git a/src/applications/drydock/management/DrydockManagementLeaseWorkflow.php b/src/applications/drydock/management/DrydockManagementLeaseWorkflow.php
index 2694d2cc64..eac3d1fab6 100644
--- a/src/applications/drydock/management/DrydockManagementLeaseWorkflow.php
+++ b/src/applications/drydock/management/DrydockManagementLeaseWorkflow.php
@@ -69,6 +69,7 @@ final class DrydockManagementLeaseWorkflow
           'number.'));
     }
 
+    $attributes = array();
     $attributes_file = $args->getArg('attributes');
     if (phutil_nonempty_string($attributes_file)) {
       if ($attributes_file == '-') {
@@ -80,9 +81,9 @@ final class DrydockManagementLeaseWorkflow
         $data = Filesystem::readFile($attributes_file);
       }
 
-      $attributes = phutil_json_decode($data);
-    } else {
-      $attributes = array();
+      if ($data) {
+        $attributes = phutil_json_decode($data);
+      }
     }
 
     $filter_identifiers = $args->getArg('blueprint');
diff --git a/src/applications/harbormaster/management/HarbormasterManagementWriteLogWorkflow.php b/src/applications/harbormaster/management/HarbormasterManagementWriteLogWorkflow.php
index 3676b1415c..b31d33602f 100644
--- a/src/applications/harbormaster/management/HarbormasterManagementWriteLogWorkflow.php
+++ b/src/applications/harbormaster/management/HarbormasterManagementWriteLogWorkflow.php
@@ -75,8 +75,12 @@ final class HarbormasterManagementWriteLogWorkflow
         pht('Writing log, slowly...'));
 
       $offset = 0;
-      $total = strlen($content);
-      $pieces = str_split($content, $rate);
+      $total = 0;
+      $pieces = array();
+      if ($content) {
+        $total = strlen($content);
+        $pieces = str_split($content, $rate);
+      }
 
       $bar = id(new PhutilConsoleProgressBar())
         ->setTotal($total);
diff --git a/src/applications/repository/storage/PhabricatorRepository.php b/src/applications/repository/storage/PhabricatorRepository.php
index 25b2364b3d..f4a6eaf949 100644
--- a/src/applications/repository/storage/PhabricatorRepository.php
+++ b/src/applications/repository/storage/PhabricatorRepository.php
@@ -2260,14 +2260,14 @@ final class PhabricatorRepository extends PhabricatorRepositoryDAO
       );
       foreach ($git_env as $key) {
         $value = getenv($key);
-        if (strlen($value)) {
+        if ($value && strlen($value)) {
           $env[$key] = $value;
         }
       }
 
       $key = 'GIT_PUSH_OPTION_COUNT';
       $git_count = getenv($key);
-      if (strlen($git_count)) {
+      if ($git_count && strlen($git_count)) {
         $git_count = (int)$git_count;
         $env[$key] = $git_count;
         for ($ii = 0; $ii < $git_count; $ii++) {
diff --git a/src/infrastructure/log/PhabricatorSSHLog.php b/src/infrastructure/log/PhabricatorSSHLog.php
index e3c15de6bf..8835e1b66b 100644
--- a/src/infrastructure/log/PhabricatorSSHLog.php
+++ b/src/infrastructure/log/PhabricatorSSHLog.php
@@ -35,7 +35,7 @@ final class PhabricatorSSHLog extends Phobject {
       }
 
       $client = getenv('SSH_CLIENT');
-      if (strlen($client)) {
+      if ($client && strlen($client)) {
         $remote_address = head(explode(' ', $client));
         $data['r'] = $remote_address;
       }
diff --git a/src/infrastructure/ssh/PhabricatorSSHWorkflow.php b/src/infrastructure/ssh/PhabricatorSSHWorkflow.php
index f7739f1332..8b2c93de8c 100644
--- a/src/infrastructure/ssh/PhabricatorSSHWorkflow.php
+++ b/src/infrastructure/ssh/PhabricatorSSHWorkflow.php
@@ -101,7 +101,7 @@ abstract class PhabricatorSSHWorkflow
 
   public function getSSHRemoteAddress() {
     $ssh_client = getenv('SSH_CLIENT');
-    if (!strlen($ssh_client)) {
+    if (!$ssh_client || !strlen($ssh_client)) {
       return null;
     }