diff --git a/src/util.cc b/src/util.cc
index c54b5ded..b28b4569 100644
--- a/src/util.cc
+++ b/src/util.cc
@@ -515,24 +515,6 @@ unsigned int hexCharToUInt(unsigned char ch)
   return ch;
 }
 
-FILE* openFile(const std::string& filename, const std::string& mode) {
-  FILE* file = fopen(filename.c_str(), mode.c_str());
-  return file;
-}
-
-bool isPowerOf(int num, int base) {
-  if(base <= 0) { return false; }
-  if(base == 1) { return true; }
-
-  while(num%base == 0) {
-    num /= base;
-    if(num == 1) {
-      return true;
-    }
-  }
-  return false;
-}
-
 std::string secfmt(time_t sec) {
   time_t tsec = sec;
   std::string str;
@@ -550,15 +532,6 @@ std::string secfmt(time_t sec) {
   return str;
 }
 
-int getNum(const char* buf, int offset, size_t length) {
-  char* temp = new char[length+1];
-  memcpy(temp, buf+offset, length);
-  temp[length] = '\0';
-  int x = strtol(temp, 0, 10);
-  delete [] temp;
-  return x;
-}
-
 namespace {
 template<typename T, typename F>
 bool parseLong(T& res, F f, const std::string& s, int base)
@@ -913,26 +886,15 @@ std::string getContentDispositionFilename(const std::string& header)
   return filename;
 }
 
-std::string randomAlpha(size_t length, const RandomizerHandle& randomizer) {
-  static const char randomChars[] =
-    "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
-  std::string str;
-  for(size_t i = 0; i < length; ++i) {
-    size_t index = randomizer->getRandomNumber(sizeof(randomChars)-1);
-    str += randomChars[index];
-  }
-  return str;
-}
-
 std::string toUpper(const std::string& src) {
   std::string temp = src;
-  std::transform(temp.begin(), temp.end(), temp.begin(), toUpperChar);
+  uppercase(temp);
   return temp;
 }
 
 std::string toLower(const std::string& src) {
   std::string temp = src;
-  std::transform(temp.begin(), temp.end(), temp.begin(), toLowerChar);
+  lowercase(temp);
   return temp;
 }
 
@@ -1110,28 +1072,6 @@ void usleep(long microseconds) {
 #endif
 }
 
-unsigned int alphaToNum(const std::string& alphabets)
-{
-  if(alphabets.empty()) {
-    return 0;
-  }
-  char base;
-  if(islower(alphabets[0])) {
-    base = 'a';
-  } else {
-    base = 'A';
-  }
-  uint64_t num = 0;
-  for(size_t i = 0, eoi = alphabets.size(); i < eoi; ++i) {
-    unsigned int v = alphabets[i]-base;
-    num = num*26+v;
-    if(num > UINT32_MAX) {
-      return 0;
-    }
-  }
-  return num;
-}
-
 void mkdirs(const std::string& dirpath)
 {
   File dir(dirpath);
diff --git a/src/util.h b/src/util.h
index f7f6009d..fecbc490 100644
--- a/src/util.h
+++ b/src/util.h
@@ -255,10 +255,6 @@ std::string fromHex(InputIterator first, InputIterator last)
   return dest;
 }
 
-FILE* openFile(const std::string& filename, const std::string& mode);
-
-bool isPowerOf(int num, int base);
-
 std::string secfmt(time_t sec);
 
 bool parseIntNoThrow(int32_t& res, const std::string& s, int base = 10);
@@ -293,9 +289,6 @@ std::string iso8859ToUtf8(const std::string& src);
 
 std::string getContentDispositionFilename(const std::string& header);
 
-std::string randomAlpha(size_t length,
-                        const SharedHandle<Randomizer>& randomizer);
-  
 std::string toUpper(const std::string& src);
 
 std::string toLower(const std::string& src);
@@ -395,15 +388,6 @@ bool isUppercase(InputIterator first, InputIterator last)
   return true;
 }
 
-/**
- * Converts alphabets to unsigned int, assuming alphabets as a base 26
- * integer and 'a' or 'A' is 0.
- * This function assumes alphabets includes only a-z.
- * Upper case are allowed but all letters must be upper case.
- * If overflow occurs, returns 0.
- */
-unsigned int alphaToNum(const std::string& alphabets);
-
 void mkdirs(const std::string& dirpath);
 
 void convertBitfield(BitfieldMan* dest, const BitfieldMan* src);
diff --git a/test/UtilTest.cc b/test/UtilTest.cc
index d6ac9d6e..9c934a40 100644
--- a/test/UtilTest.cc
+++ b/test/UtilTest.cc
@@ -40,7 +40,6 @@ class UtilTest:public CppUnit::TestFixture {
   CPPUNIT_TEST(testIstartsWith);
   // may be moved to other helper class in the future.
   CPPUNIT_TEST(testGetContentDispositionFilename);
-  CPPUNIT_TEST(testRandomAlpha);
   CPPUNIT_TEST(testToUpper);
   CPPUNIT_TEST(testToLower);
   CPPUNIT_TEST(testUppercase);
@@ -52,7 +51,6 @@ class UtilTest:public CppUnit::TestFixture {
   CPPUNIT_TEST(testIsNumber);
   CPPUNIT_TEST(testIsLowercase);
   CPPUNIT_TEST(testIsUppercase);
-  CPPUNIT_TEST(testAlphaToNum);
   CPPUNIT_TEST(testMkdirs);
   CPPUNIT_TEST(testConvertBitfield);
   CPPUNIT_TEST(testParseIntSegments);
@@ -109,7 +107,6 @@ public:
   void testIstartsWith();
   // may be moved to other helper class in the future.
   void testGetContentDispositionFilename();
-  void testRandomAlpha();
   void testToUpper();
   void testToLower();
   void testUppercase();
@@ -121,7 +118,6 @@ public:
   void testIsNumber();
   void testIsLowercase();
   void testIsUppercase();
-  void testAlphaToNum();
   void testMkdirs();
   void testConvertBitfield();
   void testParseIntSegments();
@@ -960,12 +956,6 @@ public:
   }
 };
 
-void UtilTest::testRandomAlpha() {
-  SharedHandle<Randomizer> rand(new FixedNumberRandomizer());
-  std::string s = util::randomAlpha(8, rand);
-  CPPUNIT_ASSERT_EQUAL(std::string("AAAAAAAA"), s);
-}
-
 void UtilTest::testToUpper() {
   std::string src = "608cabc0f2fa18c260cafd974516865c772363d5";
   std::string upp = "608CABC0F2FA18C260CAFD974516865C772363D5";
@@ -1134,18 +1124,6 @@ void UtilTest::testIsUppercase()
   CPPUNIT_ASSERT_EQUAL(false, util::isUppercase(s.begin(), s.end()));
 }
 
-void UtilTest::testAlphaToNum()
-{
-  CPPUNIT_ASSERT_EQUAL(0U, util::alphaToNum("a"));
-  CPPUNIT_ASSERT_EQUAL(0U, util::alphaToNum("aa"));
-  CPPUNIT_ASSERT_EQUAL(1U, util::alphaToNum("b"));
-  CPPUNIT_ASSERT_EQUAL(675U, util::alphaToNum("zz")); // 25*26+25
-  CPPUNIT_ASSERT_EQUAL(675U, util::alphaToNum("ZZ")); // 25*26+25
-  CPPUNIT_ASSERT_EQUAL(0U, util::alphaToNum(""));
-  CPPUNIT_ASSERT_EQUAL(4294967295U, util::alphaToNum("NXMRLXV"));
-  CPPUNIT_ASSERT_EQUAL(0U, util::alphaToNum("NXMRLXW")); // uint32_t overflow
-}
-
 void UtilTest::testMkdirs()
 {
   std::string dir = A2_TEST_OUT_DIR"/aria2-UtilTest-testMkdirs";