diff --git a/concordia/common/text_utils.cpp b/concordia/common/text_utils.cpp
index c7704bd..91049de 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 "utf8/utf8.h"
+
 
 TextUtils::TextUtils() {
     _lowerConverter =
@@ -11,6 +13,9 @@ TextUtils::TextUtils() {
 }
 
 std::string TextUtils::toLowerCase(const std::string & text) {
+    if (!utf8::is_valid(text.begin(), text.end())) {
+        throw ConcordiaException("Bad input encoding, use UTF-8");
+    }
     return simpleConvert(*_lowerConverter, text);
 }