diff --git a/src/future/exec/PhutilExecutableFuture.php b/src/future/exec/PhutilExecutableFuture.php
--- a/src/future/exec/PhutilExecutableFuture.php
+++ b/src/future/exec/PhutilExecutableFuture.php
@@ -143,7 +143,7 @@
 
       foreach ($known_keys as $known_key) {
         $value = getenv($known_key);
-        if (strlen($value)) {
+        if ($value && $value !== '') {
           $default_env[$known_key] = $value;
         }
       }
diff --git a/src/future/http/HTTPFuture.php b/src/future/http/HTTPFuture.php
--- a/src/future/http/HTTPFuture.php
+++ b/src/future/http/HTTPFuture.php
@@ -149,7 +149,8 @@
         $this->stateWriteComplete = true;
       }
 
-      while (($data = fread($this->socket, 32768)) || strlen($data)) {
+      while (($data = fread($this->socket, 32768)) ||
+        ($data && $data !== '')) {
         $this->response .= $data;
       }
 
diff --git a/src/toolset/workflow/ArcanistShellCompleteWorkflow.php b/src/toolset/workflow/ArcanistShellCompleteWorkflow.php
--- a/src/toolset/workflow/ArcanistShellCompleteWorkflow.php
+++ b/src/toolset/workflow/ArcanistShellCompleteWorkflow.php
@@ -194,7 +194,7 @@
     $file = $spec['file'];
     $home = getenv('HOME');
 
-    if (!strlen($home)) {
+    if (!$home || !phutil_nonempty_string($home)) {
       throw new PhutilArgumentUsageException(
         pht(
           'The "HOME" environment variable is not defined, so this workflow '.
@@ -343,7 +343,7 @@
       pht('Detecting current shell...'));
 
     $shell_env = getenv('SHELL');
-    if (!strlen($shell_env)) {
+    if (!$shell_env || !phutil_nonempty_string($shell_env)) {
       $log->writeWarning(
         pht('SHELL'),
         pht(
diff --git a/src/workflow/ArcanistPatchWorkflow.php b/src/workflow/ArcanistPatchWorkflow.php
--- a/src/workflow/ArcanistPatchWorkflow.php
+++ b/src/workflow/ArcanistPatchWorkflow.php
@@ -366,7 +366,7 @@
         case self::SOURCE_PATCH:
           if ($param == '-') {
             $patch = @file_get_contents('php://stdin');
-            if (!strlen($patch)) {
+            if (!$patch || !phutil_nonempty_string($patch)) {
               throw new ArcanistUsageException(
                 pht('Failed to read patch from stdin!'));
             }