diff --git a/CMakeLists.txt b/CMakeLists.txt
index e69b29b..2472991 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -14,8 +14,8 @@ set(PDF2HTMLEX_VERSION "0.1")
 
 set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wall -Wunused-function")
 set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++0x")
-#set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -O2")
-set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -ggdb")
+set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -O2")
+#set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -ggdb")
 
 configure_file (src/config.h.in src/config.h)
 
diff --git a/src/BackgroundRenderer.cc b/src/BackgroundRenderer.cc
index aad7f99..2a6dd3f 100644
--- a/src/BackgroundRenderer.cc
+++ b/src/BackgroundRenderer.cc
@@ -18,6 +18,6 @@ void BackgroundRenderer::drawChar(GfxState *state, double x, double y,
   double originX, double originY,
   CharCode code, int nBytes, Unicode *u, int uLen)
 {
-    SplashOutputDev::drawChar(state,x,y,dx,dy,originX,originY,code, nBytes, u, uLen);
+//    SplashOutputDev::drawChar(state,x,y,dx,dy,originX,originY,code, nBytes, u, uLen);
 }
 
diff --git a/src/util.h b/src/util.h
index 89bcf13..d44f74a 100644
--- a/src/util.h
+++ b/src/util.h
@@ -13,6 +13,7 @@
 #include <algorithm>
 #include <istream>
 #include <ostream>
+#include <iostream>
 
 #include <GfxState.h>
 #include <GfxFont.h>
@@ -27,6 +28,7 @@ using std::ostream;
 using std::noskipws;
 using std::endl;
 using std::flush;
+using std::cerr;
 
 // mute gcc warning of unused function
 namespace
@@ -75,6 +77,19 @@ static inline bool isLegalUnicode(Unicode u)
 static inline Unicode check_unicode(Unicode * u, int len, CharCode code, GfxFont * font)
 {
     Unicode private_mapping = (Unicode)(code + 0xE000);
+    if(private_mapping > 0xF8FF)
+    {
+        private_mapping = (Unicode)((private_mapping - 0xF8FF) + 0xF0000);
+        if(private_mapping > 0xFFFFD)
+        {
+            private_mapping = (Unicode)((private_mapping - 0xFFFFD) + 0x100000);
+            if(private_mapping > 0x10FFFD)
+            {
+                cerr << "Warning: all private use unicode are used" << endl;
+            }
+        }
+    }
+
 
     if(len == 0)
         return private_mapping;