diff --git a/.drone.yml b/.drone.yml
index f848e03..731e618 100644
--- a/.drone.yml
+++ b/.drone.yml
@@ -31,7 +31,7 @@ steps:
   - echo "deb http://deb.debian.org/debian sid main" >> /etc/apt/sources.list.d/sid.list
   - apt-get update -q
   - apt-get install -qy g++-6 cmake pkg-config
-  - apt-get install -qy libcurl4-openssl-dev libxdg-basedir-dev libvsqlitepp-dev libboost-system-dev libboost-filesystem-dev asciidoc catch
+  - apt-get install -qy libcurl4-openssl-dev libxdg-basedir-dev libvsqlitepp-dev libboost-system-dev libboost-filesystem-dev libicu-dev asciidoc catch
   - apt-get install -qy -t sid libcurlpp-dev
   - locale-gen en_US.UTF-8 && update-locale LANG=en_US.UTF-8
   - rm -rf build && mkdir -p build && cd build
@@ -62,7 +62,7 @@ steps:
   - apt-get update -q
   - apt-get install -qy -t xenial g++-5
   - apt-get install -qy cmake pkg-config
-  - apt-get install -qy libcurl4-openssl-dev libxdg-basedir-dev libvsqlitepp-dev libboost-system-dev libboost-filesystem-dev asciidoc catch
+  - apt-get install -qy libcurl4-openssl-dev libxdg-basedir-dev libvsqlitepp-dev libboost-system-dev libboost-filesystem-dev libicu-dev asciidoc catch
   - apt-get install -qy -t sid libcurlpp-dev
   - rm -rf build && mkdir -p build && cd build
   - cmake -DCMAKE_INSTALL_PREFIX=/usr -DWITH_MOZILLA=YES ..
@@ -90,7 +90,7 @@ steps:
   - apt-get update -q
   - apt-get install -qy -t xenial g++-9
   - apt-get install -qy cmake pkg-config
-  - apt-get install -qy libcurl4-openssl-dev libxdg-basedir-dev libvsqlitepp-dev libboost-system-dev libboost-filesystem-dev asciidoc catch
+  - apt-get install -qy libcurl4-openssl-dev libxdg-basedir-dev libvsqlitepp-dev libboost-system-dev libboost-filesystem-dev libicu-dev asciidoc catch
   - apt-get install -qy -t sid libcurlpp-dev
   - rm -rf build && mkdir -p build && cd build
   - cmake -DCMAKE_INSTALL_PREFIX=/usr -DWITH_MOZILLA=YES ..
@@ -112,7 +112,7 @@ steps:
   - echo "deb http://deb.debian.org/debian sid main" >> /etc/apt/sources.list.d/sid.list
   - apt-get update -q
   - apt-get install -qy clang cmake pkg-config
-  - apt-get install -qy libcurl4-openssl-dev libxdg-basedir-dev libvsqlitepp-dev libboost-system-dev libboost-filesystem-dev asciidoc catch
+  - apt-get install -qy libcurl4-openssl-dev libxdg-basedir-dev libvsqlitepp-dev libboost-system-dev libboost-filesystem-dev libicu-dev asciidoc catch
   - apt-get install -qy -t sid libcurlpp-dev
   - rm -rf build && mkdir -p build && cd build
   - cmake -DCMAKE_INSTALL_PREFIX=/usr -DWITH_MOZILLA=YES ..
@@ -136,7 +136,7 @@ steps:
   - apt-get update -q
   - apt-get install -qy -t stretch-backports clang-6.0
   - apt-get install -qy cmake pkg-config
-  - apt-get install -qy libcurl4-openssl-dev libxdg-basedir-dev libvsqlitepp-dev libboost-system-dev libboost-filesystem-dev asciidoc catch
+  - apt-get install -qy libcurl4-openssl-dev libxdg-basedir-dev libvsqlitepp-dev libboost-system-dev libboost-filesystem-dev libicu-dev asciidoc catch
   - apt-get install -qy -t sid libcurlpp-dev
   - rm -rf build && mkdir -p build && cd build
   - cmake -DCMAKE_INSTALL_PREFIX=/usr -DWITH_MOZILLA=YES ..
@@ -195,7 +195,7 @@ steps:
   - echo "deb http://deb.debian.org/debian sid main" >> /etc/apt/sources.list.d/sid.list
   - apt-get update -q
   - apt-get install -qy g++-6 cmake pkg-config
-  - apt-get install -qy libcurl4-openssl-dev libxdg-basedir-dev libvsqlitepp-dev libboost-system-dev libboost-filesystem-dev asciidoc catch
+  - apt-get install -qy libcurl4-openssl-dev libxdg-basedir-dev libvsqlitepp-dev libboost-system-dev libboost-filesystem-dev libicu-dev asciidoc catch
   - apt-get install -qy -t sid libcurlpp-dev
   - apt-get install -qy build-essential file
   - rm -rf build && mkdir -p build && cd build
@@ -206,32 +206,6 @@ steps:
   - name: debian-package-cache
     path: /var/cache/apt/archives
 
-# - name: rpm
-#   image: centos:7
-#   pull: always
-#   environment:
-#     CXX: /opt/rh/devtoolset-6/root/usr/bin/g++
-#     CXXFLAGS: -pipe -O2
-#   commands:
-#   - sed -i 's/keepcache=0/keepcache=1/' /etc/yum.conf
-#   - curl -s -o /var/cache/yum/epel-release-latest-7.noarch.rpm http://dl.fedoraproject.org/pub/epel/epel-release-latest-7.noarch.rpm
-#   - rpm -i /var/cache/yum/epel-release-latest-7.noarch.rpm
-#   - yum install -qy centos-release-scl
-#   - yum install -qy devtoolset-6
-#   - scl enable devtoolset-6 bash
-#   - yum install -qy libcurl-devel rpm-build libxdg-basedir-devel boost-system boost-filesystem asciidoc
-#   - yum --enablerepo=epel install -qy cmake3 vsqlite++-devel
-#   - curl -s -o /var/cache/yum/curlpp-devel-0.7.3-5.el6.x86_64.rpm https://download.fedoraproject.org/pub/epel/6/x86_64/Packages/c/curlpp-devel-0.7.3-5.el6.x86_64.rpm
-#   - curl -s -o /var/cache/yum/curlpp-0.7.3-5.el6.x86_64.rpm https://download.fedoraproject.org/pub/epel/6/x86_64/Packages/c/curlpp-0.7.3-5.el6.x86_64.rpm
-#   - yum localinstall -qy /var/cache/yum/curlpp-*
-#   - rm -rf build && mkdir -p build && cd build
-#   - cmake3 -DCMAKE_INSTALL_PREFIX=/usr -DWITH_RPM=YES ..
-#   - make package
-#   - cp -v remwharead-${DRONE_TAG}-0.x86_64.rpm ..
-#   volumes:
-#   - name: centos-package-cache
-#     path: /var/cache/yum
-
 - name: release
   image: plugins/gitea-release
   pull: always
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 04e7663..b664bd4 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,6 +1,6 @@
 cmake_minimum_required (VERSION 3.2)
 project(remwharead
-  VERSION 0.6.0
+  VERSION 0.6.1
   LANGUAGES CXX
 )
 
@@ -17,6 +17,7 @@ pkg_check_modules(LIBXDG_BASEDIR REQUIRED libxdg-basedir)
 # because the sqlite3 in Debian jessie doesn't come with a pkg-config module.
 pkg_check_modules(SQLITE3 sqlite3)
 pkg_check_modules(CURLPP REQUIRED curlpp)
+find_package(ICU COMPONENTS uc i18n REQUIRED)
 
 set(CMAKE_CXX_STANDARD 14)
 set(CMAKE_CXX_STANDARD_REQUIRED ON)
@@ -32,13 +33,16 @@ Include_directories(${PROJECT_BINARY_DIR})
 include_directories(${LIBXDG_BASEDIR_INCLUDE_DIRS})
 include_directories(${SQLITE3_INCLUDE_DIRS})
 include_directories(${CURLPP_INCLUDE_DIRS})
+include_directories(${ICU_INCLUDE_DIRS})
 
 link_directories(${LIBXDG_BASEDIR_LIBRARY_DIRS})
 link_directories(${SQLITE3_LIBRARY_DIRS})
 link_directories(${CURLPP_LIBRARY_DIRS})
+link_directories(${ICU_LIBRARY_DIRS})
 
 set(COMMON_LIBRARIES
-  ${LIBXDG_BASEDIR_LIBRARIES} vsqlitepp stdc++fs ${CURLPP_LIBRARIES})
+  ${LIBXDG_BASEDIR_LIBRARIES} vsqlitepp stdc++fs ${CURLPP_LIBRARIES}
+  ${ICU_LIBRARIES})
 
 # Write version in header
 configure_file(
diff --git a/README.adoc b/README.adoc
index efbea27..6318fd8 100644
--- a/README.adoc
+++ b/README.adoc
@@ -55,6 +55,7 @@ only.
 * http://repo.or.cz/w/libxdg-basedir.git[libxdg-basedir] (tested: 1.2)
 * http://www.curlpp.org/[curlpp] (tested: 0.8 / 0.7)
 * http://vsqlite.virtuosic-bytes.com/[vsqlite++] (tested: 0.3)
+* http://www.icu-project.org/[ICU] (tested: 64.2 / 57.1)
 * Optional:
 ** Manpage: http://asciidoc.org/[asciidoc] (tested: 8.6)
 ** Tests: https://github.com/catchorg/Catch2[catch] (tested: 2.5 / 1.2)
diff --git a/src/search.cpp b/src/search.cpp
index 564896e..2be2d0c 100644
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -17,7 +17,7 @@
 #include <regex>
 #include <algorithm>
 #include <locale>
-#include <codecvt>
+#include <unicode/unistr.h>
 #include "search.hpp"
 
 using std::regex;
@@ -63,11 +63,9 @@ const vector<vector<string>> parse_expression(string expression)
 
 const string to_lowercase(const string &str)
 {
+    icu::UnicodeString uni(str.c_str());
     string out;
-    std::locale loc("");
-    const std::ctype<char>& ct = std::use_facet<std::ctype<char>>(loc);
-    std::transform(str.begin(), str.end(), std::back_inserter(out),
-                   std::bind1st(std::mem_fun(&std::ctype<char>::tolower), &ct));
+    uni.toLower().toUTF8String(out);
     return out;
 }