diff --git a/concordia/common/text_utils.cpp b/concordia/common/text_utils.cpp
index 91049de..902c392 100644
--- a/concordia/common/text_utils.cpp
+++ b/concordia/common/text_utils.cpp
@@ -2,6 +2,8 @@
 #include <boost/algorithm/string.hpp>
 #include <boost/algorithm/string/case_conv.hpp>
 #include <boost/locale.hpp>
+#include <string>
+#include <algorithm>
 #include "utf8/utf8.h"
 
 
@@ -12,9 +14,18 @@ TextUtils::TextUtils() {
         StringCaseConverterManager::getInstance().getUpperCaseConverter("pl");
 }
 
+char TextUtils::_easytolower(char in) {
+    if(in <= 'Z' && in >= 'A') {
+        return in - ('Z' - 'z');
+    }
+    return in;
+}
+
 std::string TextUtils::toLowerCase(const std::string & text) {
     if (!utf8::is_valid(text.begin(), text.end())) {
-        throw ConcordiaException("Bad input encoding, use UTF-8");
+        std::string data = text;
+        std::transform(data.begin(), data.end(), data.begin(), TextUtils::_easytolower);
+        return data;
     }
     return simpleConvert(*_lowerConverter, text);
 }
diff --git a/concordia/common/text_utils.hpp b/concordia/common/text_utils.hpp
index de83d1e..5c4f92a 100644
--- a/concordia/common/text_utils.hpp
+++ b/concordia/common/text_utils.hpp
@@ -41,6 +41,8 @@ private:
 
     void operator=(TextUtils const&);                  // Don't implement
 
+    static char _easytolower(char in);
+
     boost::shared_ptr<StringGeneralCaseConverter> _lowerConverter;
 
     boost::shared_ptr<StringGeneralCaseConverter> _upperConverter;
diff --git a/concordia/t/test_concordia.cpp b/concordia/t/test_concordia.cpp
index f0c008a..2d5063c 100644
--- a/concordia/t/test_concordia.cpp
+++ b/concordia/t/test_concordia.cpp
@@ -571,4 +571,16 @@ BOOST_AUTO_TEST_CASE( TokenizeOnly )
 
 }
 
+BOOST_AUTO_TEST_CASE( TokenizeBadUtf )
+{
+    Concordia concordia = Concordia(TestResourcesManager::getTempPath(),
+                                    TestResourcesManager::getTestConcordiaConfigFilePath("concordia.cfg"));
+    TokenizedSentence ts = concordia.tokenize("Ala \xc3\x28 23 --- ..//,./ '''8902347 poSiaDa KOTA", false, false);
+
+    BOOST_CHECK_EQUAL(ts.getTokenizedSentence(), "ala ne_number ne_number posiada kota");
+
+    concordia.clearIndex();
+
+}
+
 BOOST_AUTO_TEST_SUITE_END()