diff --git a/src/lint/linter/ArcanistCSharpLinter.php b/src/lint/linter/ArcanistCSharpLinter.php
--- a/src/lint/linter/ArcanistCSharpLinter.php
+++ b/src/lint/linter/ArcanistCSharpLinter.php
@@ -195,7 +195,7 @@
 
   protected function resolveFuture(Future $future) {
     list($stdout) = $future->resolvex();
-    $all_results = json_decode($stdout);
+    $all_results = phutil_json_decode($stdout);
     foreach ($all_results as $results) {
       if ($results === null || $results->Issues === null) {
         return;
diff --git a/src/lint/linter/ArcanistJSHintLinter.php b/src/lint/linter/ArcanistJSHintLinter.php
--- a/src/lint/linter/ArcanistJSHintLinter.php
+++ b/src/lint/linter/ArcanistJSHintLinter.php
@@ -132,14 +132,14 @@
   }
 
   protected function parseLinterOutput($path, $err, $stdout, $stderr) {
-    $errors = json_decode($stdout, true);
-
-    if (!is_array($errors)) {
+    $errors = null;
+    try {
+      $error = phutil_json_decode($stdout);
+    } catch (PhutilJSONParserException $ex) {
       // Something went wrong and we can't decode the output. Exit abnormally.
-      throw new RuntimeException(
-        "JSHint returned unparseable output.\n".
-        "stdout:\n\n{$stdout}".
-        "stderr:\n\n{$stderr}");
+      throw new PhutilProxyException(
+        pht('JSHint returned unparseable output.'),
+        $ex);
     }
 
     $messages = array();
diff --git a/src/unit/parser/ArcanistPhpunitTestResultParser.php b/src/unit/parser/ArcanistPhpunitTestResultParser.php
--- a/src/unit/parser/ArcanistPhpunitTestResultParser.php
+++ b/src/unit/parser/ArcanistPhpunitTestResultParser.php
@@ -172,10 +172,7 @@
 
     $json = preg_replace('/}{\s*"/', '},{"', $json);
     $json = '['.$json.']';
-    $json = json_decode($json);
-    if (!is_array($json)) {
-      throw new Exception('JSON could not be decoded');
-    }
+    $json = phutil_json_decode($json);
 
     return $json;
   }
diff --git a/src/workflow/ArcanistCallConduitWorkflow.php b/src/workflow/ArcanistCallConduitWorkflow.php
--- a/src/workflow/ArcanistCallConduitWorkflow.php
+++ b/src/workflow/ArcanistCallConduitWorkflow.php
@@ -67,8 +67,9 @@
         pht('Waiting for JSON parameters on stdin...'));
     }
     $params = @file_get_contents('php://stdin');
-    $params = json_decode($params, true);
-    if (!is_array($params)) {
+    try {
+      $params = phutil_json_decode($params);
+    } catch (PhutilJSONParserException $ex) {
       throw new ArcanistUsageException(
         pht('Provide method parameters on stdin as a JSON blob.'));
     }