diff --git a/src/FontLib/Glyph/Outline.php b/src/FontLib/Glyph/Outline.php
index 639ff60..b64aff2 100644
--- a/src/FontLib/Glyph/Outline.php
+++ b/src/FontLib/Glyph/Outline.php
@@ -48,7 +48,7 @@ class Outline extends BinaryStream {
   static function init(glyf $table, $offset, $size, BinaryStream $font) {
     $font->seek($offset);
 
-    if ($font->readInt16() > -1) {
+    if ($size === 0 || $font->readInt16() > -1) {
       /** @var OutlineSimple $glyph */
       $glyph = new OutlineSimple($table, $offset, $size);
     }
diff --git a/src/FontLib/Table/Type/cmap.php b/src/FontLib/Table/Type/cmap.php
index d09b0dc..fb70f11 100644
--- a/src/FontLib/Table/Type/cmap.php
+++ b/src/FontLib/Table/Type/cmap.php
@@ -125,6 +125,10 @@ protected function _parse() {
           }
 
           for ($c = $c1; $c <= $c2; $c++) {
+            if ($c === 0xFFFF) {
+              continue;
+            }
+
             if ($ro == 0) {
               $gid = ($c + $d) & 0xFFFF;
             }
@@ -132,15 +136,17 @@ protected function _parse() {
               $offset = ($c - $c1) * 2 + $ro;
               $offset = $ro_start + 2 * $i + $offset;
 
-              $font->seek($offset);
-              $gid = $font->readUInt16();
+              $gid = 0;
+              if ($font->seek($offset) === true) {
+                $gid = $font->readUInt16();
+              }
 
               if ($gid != 0) {
                 $gid = ($gid + $d) & 0xFFFF;
               }
             }
 
-            if ($gid > 0) {
+            if ($gid >= 0) {
               $glyphIndexArray[$c] = $gid;
             }
           }