diff --git a/src/utils/utils.php b/src/utils/utils.php
index 5e5f305..4854681 100644
--- a/src/utils/utils.php
+++ b/src/utils/utils.php
@@ -770,6 +770,19 @@ function phutil_split_lines($corpus, $retain_endings = true) {
     return array('');
   }
 
+  $count = substr_count($corpus, "\n");
+  $limit = 1024 * 1024;
+  if ($count > $limit) {
+    $ex = new Exception(
+      pht(
+        'Huge input! Found %s lines, hoped for %s. Probably about to '.
+        'OOM. Exciting! Corpus begins: %s...',
+        new PhutilNumber($count),
+        new Phutilnumber($limit),
+        tsprintf("%s", substr($corpus, 0, 256))));
+    phlog($ex);
+  }
+
   // Split on "\r\n" or "\n".
   if ($retain_endings) {
     $lines = preg_split('/(?<=\n)/', $corpus);