diff --git a/src/aphront/sink/AphrontHTTPSink.php b/src/aphront/sink/AphrontHTTPSink.php
--- a/src/aphront/sink/AphrontHTTPSink.php
+++ b/src/aphront/sink/AphrontHTTPSink.php
@@ -33,7 +33,7 @@
    * @return void
    */
   final public function writeHTTPStatus($code, $message = '') {
-    if (!preg_match('/^\d{3}$/', $code)) {
+    if (!preg_match('/^\d{3}$/', (string)$code)) {
       throw new Exception(pht("Malformed HTTP status code '%s'!", $code));
     }
 
diff --git a/src/applications/aphlict/management/PhabricatorAphlictManagementWorkflow.php b/src/applications/aphlict/management/PhabricatorAphlictManagementWorkflow.php
--- a/src/applications/aphlict/management/PhabricatorAphlictManagementWorkflow.php
+++ b/src/applications/aphlict/management/PhabricatorAphlictManagementWorkflow.php
@@ -392,7 +392,7 @@
         "%s\n",
         pht('Starting Aphlict server in foreground...'));
     } else {
-      Filesystem::writeFile($this->getPIDPath(), getmypid());
+      Filesystem::writeFile($this->getPIDPath(), (string)getmypid());
     }
 
     $command = $this->getStartCommand($this->getServerArgv());
diff --git a/src/applications/auth/factor/PhabricatorTOTPAuthFactor.php b/src/applications/auth/factor/PhabricatorTOTPAuthFactor.php
--- a/src/applications/auth/factor/PhabricatorTOTPAuthFactor.php
+++ b/src/applications/auth/factor/PhabricatorTOTPAuthFactor.php
@@ -403,7 +403,7 @@
             ((ord($hash[$offset + 3])       )      );
 
     $code = ($code % 1000000);
-    $code = str_pad($code, 6, '0', STR_PAD_LEFT);
+    $code = str_pad((string)$code, 6, '0', STR_PAD_LEFT);
 
     return $code;
   }
diff --git a/src/applications/config/check/PhabricatorWebServerSetupCheck.php b/src/applications/config/check/PhabricatorWebServerSetupCheck.php
--- a/src/applications/config/check/PhabricatorWebServerSetupCheck.php
+++ b/src/applications/config/check/PhabricatorWebServerSetupCheck.php
@@ -43,7 +43,7 @@
       ->replaceQueryParam($expect_key, $expect_value);
 
     $self_future = id(new HTTPSFuture($base_uri))
-      ->addHeader('X-Setup-SelfCheck', 1)
+      ->addHeader('X-Setup-SelfCheck', '1')
       ->addHeader('Accept-Encoding', 'gzip')
       ->setDisableContentDecoding(true)
       ->setHTTPBasicAuthCredentials(
@@ -56,7 +56,7 @@
       $gzip_compressed = gzencode($gzip_uncompressed);
 
       $gzip_future = id(new HTTPSFuture($base_uri))
-        ->addHeader('X-Setup-SelfCheck', 1)
+        ->addHeader('X-Setup-SelfCheck', '1')
         ->addHeader('Content-Encoding', 'gzip')
         ->setMethod('POST')
         ->setTimeout(5)
diff --git a/src/applications/differential/controller/DifferentialRevisionAffectedPathsController.php b/src/applications/differential/controller/DifferentialRevisionAffectedPathsController.php
--- a/src/applications/differential/controller/DifferentialRevisionAffectedPathsController.php
+++ b/src/applications/differential/controller/DifferentialRevisionAffectedPathsController.php
@@ -87,7 +87,7 @@
     }
 
     // Sort rows by path name.
-    $rows = isort($rows, 3);
+    $rows = isort($rows, '3');
 
     $table_view = id(new AphrontTableView($rows))
       ->setNoDataString(pht('This revision has no indexed affected paths.'))
diff --git a/src/applications/feed/PhabricatorFeedStoryPublisher.php b/src/applications/feed/PhabricatorFeedStoryPublisher.php
--- a/src/applications/feed/PhabricatorFeedStoryPublisher.php
+++ b/src/applications/feed/PhabricatorFeedStoryPublisher.php
@@ -321,7 +321,7 @@
       // We're on a 32-bit machine.
       if (function_exists('bcadd')) {
         // Try to use the 'bc' extension.
-        return bcadd(bcmul($time, bcpow(2, 32)), $rand);
+        return bcadd(bcmul($time, bcpow('2', '32')), $rand);
       } else {
         // Do the math in MySQL. TODO: If we formalize a bc dependency, get
         // rid of this.
diff --git a/src/applications/feed/storage/PhabricatorFeedStoryData.php b/src/applications/feed/storage/PhabricatorFeedStoryData.php
--- a/src/applications/feed/storage/PhabricatorFeedStoryData.php
+++ b/src/applications/feed/storage/PhabricatorFeedStoryData.php
@@ -45,7 +45,7 @@
       // We're on a 32-bit machine.
       if (function_exists('bcadd')) {
         // Try to use the 'bc' extension.
-        return bcdiv($this->chronologicalKey, bcpow(2, 32));
+        return bcdiv($this->chronologicalKey, bcpow('2', '32'));
       } else {
         // Do the math in MySQL. TODO: If we formalize a bc dependency, get
         // rid of this.
diff --git a/src/applications/files/engine/PhabricatorLocalDiskFileStorageEngine.php b/src/applications/files/engine/PhabricatorLocalDiskFileStorageEngine.php
--- a/src/applications/files/engine/PhabricatorLocalDiskFileStorageEngine.php
+++ b/src/applications/files/engine/PhabricatorLocalDiskFileStorageEngine.php
@@ -47,7 +47,7 @@
     // have one directory with a zillion files in it, since this is generally
     // bad news.
     do {
-      $name = md5(mt_rand());
+      $name = md5((string)mt_rand());
       $name = preg_replace('/^(..)(..)(.*)$/', '\\1/\\2/\\3', $name);
       if (!Filesystem::pathExists($root.'/'.$name)) {
         break;
diff --git a/src/applications/metamta/controller/PhabricatorMetaMTAMailViewController.php b/src/applications/metamta/controller/PhabricatorMetaMTAMailViewController.php
--- a/src/applications/metamta/controller/PhabricatorMetaMTAMailViewController.php
+++ b/src/applications/metamta/controller/PhabricatorMetaMTAMailViewController.php
@@ -194,7 +194,7 @@
     }
 
     // Sort headers by name.
-    $headers = isort($headers, 0);
+    $headers = isort($headers, '0');
 
     foreach ($headers as $header) {
       list($key, $value) = $header;
diff --git a/src/applications/phrequent/storage/PhrequentTimeBlock.php b/src/applications/phrequent/storage/PhrequentTimeBlock.php
--- a/src/applications/phrequent/storage/PhrequentTimeBlock.php
+++ b/src/applications/phrequent/storage/PhrequentTimeBlock.php
@@ -259,7 +259,7 @@
    * @return list<pair<int, int>> Nonoverlapping time ranges.
    */
   public static function mergeTimeRanges(array $ranges) {
-    $ranges = isort($ranges, 0);
+    $ranges = isort($ranges, '0');
 
     $result = array();
 
diff --git a/src/applications/search/engine/PhabricatorSearchNgramEngine.php b/src/applications/search/engine/PhabricatorSearchNgramEngine.php
--- a/src/applications/search/engine/PhabricatorSearchNgramEngine.php
+++ b/src/applications/search/engine/PhabricatorSearchNgramEngine.php
@@ -35,6 +35,7 @@
 
     $ngrams = array();
     foreach ($unique_tokens as $token => $ignored) {
+      $token = (string)$token;
       $token_v = phutil_utf8v($token);
       $length = count($token_v);
 
diff --git a/src/applications/settings/panel/PhabricatorEmailPreferencesSettingsPanel.php b/src/applications/settings/panel/PhabricatorEmailPreferencesSettingsPanel.php
--- a/src/applications/settings/panel/PhabricatorEmailPreferencesSettingsPanel.php
+++ b/src/applications/settings/panel/PhabricatorEmailPreferencesSettingsPanel.php
@@ -120,7 +120,7 @@
     }
 
     // Sort them, then put "Common" at the top.
-    $tag_groups = isort($tag_groups, 0);
+    $tag_groups = isort($tag_groups, '0');
     if ($common_tags) {
       array_unshift($tag_groups, array(pht('Common'), $common_tags));
     }
diff --git a/src/applications/xhprof/view/PhabricatorXHProfProfileSymbolView.php b/src/applications/xhprof/view/PhabricatorXHProfProfileSymbolView.php
--- a/src/applications/xhprof/view/PhabricatorXHProfProfileSymbolView.php
+++ b/src/applications/xhprof/view/PhabricatorXHProfProfileSymbolView.php
@@ -93,7 +93,7 @@
         $data[$key]['wt'] / $flat[$symbol]['wt'],
       );
     }
-    $child_rows = isort($child_rows, 2);
+    $child_rows = isort($child_rows, '2');
     $child_rows = array_reverse($child_rows);
     $rows = array_merge(
       $rows,
diff --git a/src/infrastructure/edges/query/PhabricatorEdgeQuery.php b/src/infrastructure/edges/query/PhabricatorEdgeQuery.php
--- a/src/infrastructure/edges/query/PhabricatorEdgeQuery.php
+++ b/src/infrastructure/edges/query/PhabricatorEdgeQuery.php
@@ -122,7 +122,7 @@
    * use case.
    *
    * @param string  $src_phid Source PHID.
-   * @param string $edge_type Edge type constant.
+   * @param string  $edge_type Edge type constant.
    * @return list<string> List of destination PHIDs.
    */
   public static function loadDestinationPHIDs($src_phid, $edge_type) {