diff --git a/taglib/mpeg/id3v2/id3v2framefactory.cpp b/taglib/mpeg/id3v2/id3v2framefactory.cpp
index 1d39a713..323e8091 100644
--- a/taglib/mpeg/id3v2/id3v2framefactory.cpp
+++ b/taglib/mpeg/id3v2/id3v2framefactory.cpp
@@ -412,10 +412,11 @@ void FrameFactory::updateGenre(TextIdentificationFrame *frame) const
     if(s.startsWith("(") && end > 0) {
       // "(12)Genre"
       String text = s.substr(end + 1);
-      int number = s.substr(1, end - 1).toInt();
-      if (number > 0 && number <= 255 && !(ID3v1::genre(number) == text))
+      bool ok;
+      int number = s.substr(1, end - 1).toInt(&ok);
+      if(ok && number >= 0 && number <= 255 && !(ID3v1::genre(number) == text))
         newfields.append(s.substr(1, end - 1));
-      if (!text.isEmpty())
+      if(!text.isEmpty())
         newfields.append(text);
     }
     else {
diff --git a/taglib/mpeg/id3v2/id3v2tag.cpp b/taglib/mpeg/id3v2/id3v2tag.cpp
index 1d4e8d4c..2ef00270 100644
--- a/taglib/mpeg/id3v2/id3v2tag.cpp
+++ b/taglib/mpeg/id3v2/id3v2tag.cpp
@@ -164,19 +164,10 @@ String ID3v2::Tag::genre() const
     if((*it).isEmpty())
       continue;
 
-    bool isNumber = true;
-
-    for(String::ConstIterator charIt = (*it).begin();
-        isNumber && charIt != (*it).end();
-        ++charIt)
-    {
-      isNumber = *charIt >= '0' && *charIt <= '9';
-    }
-
-    if(isNumber) {
-      int number = (*it).toInt();
-      if(number >= 0 && number <= 255)
-        *it = ID3v1::genre(number);
+    bool ok;
+    int number = (*it).toInt(&ok);
+    if(ok && number >= 0 && number <= 255) {
+      *it = ID3v1::genre(number);
     }
 
     if(std::find(genres.begin(), genres.end(), *it) == genres.end())
diff --git a/taglib/toolkit/tstring.cpp b/taglib/toolkit/tstring.cpp
index 755a8770..876575b6 100644
--- a/taglib/toolkit/tstring.cpp
+++ b/taglib/toolkit/tstring.cpp
@@ -431,18 +431,28 @@ ByteVector String::data(Type t) const
 }
 
 int String::toInt() const
+{
+  return toInt(0);
+}
+
+int String::toInt(bool *ok) const
 {
   int value = 0;
 
-  bool negative = d->data[0] == '-';
-  uint i = negative ? 1 : 0;
+  uint size = d->data.size();
+  bool negative = size > 0 && d->data[0] == '-';
+  uint start = negative ? 1 : 0;
+  uint i = start;
 
-  for(; i < d->data.size() && d->data[i] >= '0' && d->data[i] <= '9'; i++)
+  for(; i < size && d->data[i] >= '0' && d->data[i] <= '9'; i++)
     value = value * 10 + (d->data[i] - '0');
 
   if(negative)
     value = value * -1;
 
+  if(ok)
+    *ok = (size > start && i == size);
+
   return value;
 }
 
diff --git a/taglib/toolkit/tstring.h b/taglib/toolkit/tstring.h
index 9289f7da..6534b923 100644
--- a/taglib/toolkit/tstring.h
+++ b/taglib/toolkit/tstring.h
@@ -291,9 +291,21 @@ namespace TagLib {
 
     /*!
      * Convert the string to an integer.
+     *
+     * Returns the integer if the conversion was successfull or 0 if the
+     * string does not represent a number.
      */
     int toInt() const;
 
+    /*!
+     * Convert the string to an integer.
+     *
+     * If the conversion was successfull, it sets the value of \a *ok to
+     * true and returns the integer. Otherwise it sets \a *ok to false
+     * and the result is undefined.
+     */
+    int toInt(bool *ok) const;
+
     /*!
      * Returns a string with the leading and trailing whitespace stripped.
      */
diff --git a/tests/test_string.cpp b/tests/test_string.cpp
index f677d059..b6ff972e 100644
--- a/tests/test_string.cpp
+++ b/tests/test_string.cpp
@@ -40,6 +40,7 @@ class TestString : public CppUnit::TestFixture
   CPPUNIT_TEST(testUTF16DecodeEmptyWithBOM);
   CPPUNIT_TEST(testAppendCharDetach);
   CPPUNIT_TEST(testAppendStringDetach);
+  CPPUNIT_TEST(testToInt);
   CPPUNIT_TEST_SUITE_END();
 
 public:
@@ -165,6 +166,33 @@ public:
     CPPUNIT_ASSERT_EQUAL(3, String("foo.bar").rfind("."));
   }
 
+  void testToInt()
+  {
+    bool ok;
+    CPPUNIT_ASSERT_EQUAL(String("123").toInt(&ok), 123);
+    CPPUNIT_ASSERT_EQUAL(ok, true);
+
+    CPPUNIT_ASSERT_EQUAL(String("-123").toInt(&ok), -123);
+    CPPUNIT_ASSERT_EQUAL(ok, true);
+
+    CPPUNIT_ASSERT_EQUAL(String("abc").toInt(&ok), 0);
+    CPPUNIT_ASSERT_EQUAL(ok, false);
+
+    CPPUNIT_ASSERT_EQUAL(String("1x").toInt(&ok), 1);
+    CPPUNIT_ASSERT_EQUAL(ok, false);
+
+    CPPUNIT_ASSERT_EQUAL(String("").toInt(&ok), 0);
+    CPPUNIT_ASSERT_EQUAL(ok, false);
+
+    CPPUNIT_ASSERT_EQUAL(String("-").toInt(&ok), 0);
+    CPPUNIT_ASSERT_EQUAL(ok, false);
+
+    CPPUNIT_ASSERT_EQUAL(String("123").toInt(), 123);
+    CPPUNIT_ASSERT_EQUAL(String("-123").toInt(), -123);
+    CPPUNIT_ASSERT_EQUAL(String("123aa").toInt(), 123);
+    CPPUNIT_ASSERT_EQUAL(String("-123aa").toInt(), -123);
+  }
+
 };
 
 CPPUNIT_TEST_SUITE_REGISTRATION(TestString);