diff --git a/src/include/util.h b/src/include/util.h
index a8745dd..1284837 100644
--- a/src/include/util.h
+++ b/src/include/util.h
@@ -18,8 +18,6 @@
 #include <string>
 #include <map>
 
-#include <UTF8.h>
-
 #ifndef nullptr
 #define nullptr (NULL)
 #endif
@@ -38,16 +36,6 @@ extern const std::map<std::string, std::string> GB_ENCODED_FONT_NAME_MAP;
 // value: (prefix string, suffix string)
 extern const std::map<std::pair<std::string, bool>, std::pair<std::string, std::string> > EMBED_STRING_MAP;
 
-// mute gcc warning of unused function
-namespace
-{
-    template <class T>
-    void _(){ 
-        auto _1 = &mapUCS2; 
-        auto _2 = &mapUTF8;
-    }
-}
-
 static inline double _round(double x) { return (std::abs(x) > EPS) ? x : 0.0; }
 static inline bool _equal(double x, double y) { return std::abs(x-y) < EPS; }
 static inline bool _is_positive(double x) { return x > EPS; }
diff --git a/src/util.cc b/src/util.cc
index ed41550..2c854f3 100644
--- a/src/util.cc
+++ b/src/util.cc
@@ -123,6 +123,45 @@ Unicode check_unicode(Unicode * u, int len, CharCode code, GfxFont * font)
     return unicode_from_font(code, font);
 }
 
+/*
+ * Copied from UTF.h / UTF8.h in poppler
+ */
+static int mapUTF8(Unicode u, char *buf, int bufSize) {
+  if        (u <= 0x0000007f) {
+    if (bufSize < 1) {
+      return 0;
+    }
+    buf[0] = (char)u;
+    return 1;
+  } else if (u <= 0x000007ff) {
+    if (bufSize < 2) {
+      return 0;
+    }
+    buf[0] = (char)(0xc0 + (u >> 6));
+    buf[1] = (char)(0x80 + (u & 0x3f));
+    return 2;
+  } else if (u <= 0x0000ffff) {
+    if (bufSize < 3) {
+      return 0;
+    }
+    buf[0] = (char)(0xe0 + (u >> 12));
+    buf[1] = (char)(0x80 + ((u >> 6) & 0x3f));
+    buf[2] = (char)(0x80 + (u & 0x3f));
+    return 3;
+  } else if (u <= 0x0010ffff) {
+    if (bufSize < 4) {
+      return 0;
+    }
+    buf[0] = (char)(0xf0 + (u >> 18));
+    buf[1] = (char)(0x80 + ((u >> 12) & 0x3f));
+    buf[2] = (char)(0x80 + ((u >> 6) & 0x3f));
+    buf[3] = (char)(0x80 + (u & 0x3f));
+    return 4;
+  } else {
+    return 0;
+  }
+}
+
 void outputUnicodes(ostream & out, const Unicode * u, int uLen)
 {
     for(int i = 0; i < uLen; ++i)