diff --git a/CMakeLists.txt b/CMakeLists.txt
index 9861e7d..c937052 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -9,7 +9,7 @@ option(ENABLE_SVG "Enable SVG support, for generating SVG background images and
 
 include_directories(${CMAKE_SOURCE_DIR}/src)
 
-set(PDF2HTMLEX_VERSION "0.13.4")
+set(PDF2HTMLEX_VERSION "0.13.5")
 set(ARCHIVE_NAME pdf2htmlex-${PDF2HTMLEX_VERSION})
 add_custom_target(dist
     COMMAND git archive --prefix=${ARCHIVE_NAME}/ HEAD
diff --git a/src/util/unicode.cc b/src/util/unicode.cc
index 76efc89..8e278a3 100644
--- a/src/util/unicode.cc
+++ b/src/util/unicode.cc
@@ -77,16 +77,14 @@ bool isLegalUnicode(Unicode u)
     if(u < max_small_unicode)
         return valid_small_unicode[u];
 
-    /*
-     * U+2029: Paragraph Separator
-     * TODO: check U+2028 etc
-     */
-    if(u == 0x2029)
-        return false;
 
-    /*
-     * Reserved code for utf-16
-     */
+    // * U+200B: zero width space
+    if(u == 0x200b) return false;
+
+    // * U+2029: paragraph separator
+    if(u == 0x2029) return false;
+
+    // Reserved code for utf-16
     if((u >= 0xd800) && (u <= 0xdfff))
         return false;