diff --git a/scripts/php_extension_functions.txt b/scripts/php_extension_functions.txt
index 12170be1..a540920f 100644
--- a/scripts/php_extension_functions.txt
+++ b/scripts/php_extension_functions.txt
@@ -111,6 +111,7 @@ imagecreatefrompng
 imagecreatefromstring
 imagecreatefromwbmp
 imagecreatefromxbm
+imagecreatefromxpm
 imagecreatetruecolor
 imagedashedline
 imagedestroy
@@ -124,10 +125,14 @@ imagefilltoborder
 imagefilter
 imagefontheight
 imagefontwidth
+imageftbbox
+imagefttext
 imagegammacorrect
 imagegd
 imagegd2
 imagegif
+imagegrabscreen
+imagegrabwindow
 imageinterlace
 imageistruecolor
 imagejpeg
@@ -137,6 +142,13 @@ imageloadfont
 imagepalettecopy
 imagepng
 imagepolygon
+imagepsbbox
+imagepsencodefont
+imagepsextendfont
+imagepsfreefont
+imagepsloadfont
+imagepsslantfont
+imagepstext
 imagerectangle
 imagerotate
 imagesavealpha
@@ -150,6 +162,8 @@ imagestringup
 imagesx
 imagesy
 imagetruecolortopalette
+imagettfbbox
+imagettftext
 imagetypes
 imagewbmp
 imagexbm
diff --git a/src/workflow/ArcanistLintWorkflow.php b/src/workflow/ArcanistLintWorkflow.php
index b79452e1..054e409e 100644
--- a/src/workflow/ArcanistLintWorkflow.php
+++ b/src/workflow/ArcanistLintWorkflow.php
@@ -548,7 +548,10 @@ EOTEXT
             $cached_path[] = $message->toDictionary();
           }
         }
-        $hash = $file_hashes[$abs_path];
+        $hash = idx($file_hashes, $abs_path);
+        if (!$hash) {
+          $hash = md5_file($abs_path);
+        }
         $cached[$path] = array($hash => array($version => $cached_path));
       }
       $cache[$this->getCacheKey()] = $cached;