QtCore не найден

У меня проблема с установкой - когда я хочу скомпилировать KeePassX с cmake, возникает ошибка с QtCore. Я попытался установить libqtcore, я получил E: Unable to locate package libqt4-core
Выходные данные компиляции KeePassX:

cmake [-DCMAKE_INSTALL_PREFIX=/usr/local] ..
-- The C compiler identification is GNU 5.3.1
-- The CXX compiler identification is GNU 5.3.1
-- Check for working C compiler: /usr/bin/cc
-- Check for working C compiler: /usr/bin/cc -- works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Detecting C compile features
-- Detecting C compile features - done
-- Check for working CXX compiler: /usr/bin/c++
-- Check for working CXX compiler: /usr/bin/c++ -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Performing Test WERROR_C_AVAILABLE
-- Performing Test WERROR_C_AVAILABLE - Success
-- Performing Test WERROR_CXX_AVAILABLE
-- Performing Test WERROR_CXX_AVAILABLE - Success
CMake Warning at /usr/share/cmake-3.5/Modules/FindQt4.cmake:626 (message):
  /usr/bin/qmake reported QT_INSTALL_LIBS as "/usr/lib/x86_64-linux-gnu" but
  QtCore could not be found there.  Qt is NOT installed correctly for the
  target build environment.
Call Stack (most recent call first):
  CMakeLists.txt:151 (find_package)


CMake Error at /usr/share/cmake-3.5/Modules/FindQt4.cmake:634 (message):
  Could NOT find QtCore.  Check
  /home/mike/Downloads/keepassx-2.0.2/build/CMakeFiles/CMakeError.log for
  more details.
Call Stack (most recent call first):
  CMakeLists.txt:151 (find_package)


-- Configuring incomplete, errors occurred!  

Выходные данные после попытки установить Qt с sudo apt install libqtcore4:

sudo apt install libqtcore4
[sudo] password for mike: 
Reading package lists... Done
Building dependency tree       
Reading state information... Done
libqtcore4 is already the newest version (4:4.8.7+dfsg-5ubuntu2).
libqtcore4 set to manually installed.
The following packages were automatically installed and are no longer required:
  ca-certificates-mono cli-common kde-l10n-cs kde-l10n-engb
  libmono-corlib2.0-cil libmono-corlib4.5-cil libmono-i18n-west4.0-cil
  libmono-i18n4.0-cil libmono-security4.0-cil
  libmono-system-configuration4.0-cil libmono-system-security4.0-cil
  libmono-system-xml4.0-cil libmono-system4.0-cil libmonoboehm-2.0-1
  libpkcs11-helper1 mono-4.0-gac mono-gac mono-runtime mono-runtime-common
  mono-runtime-sgen mono-utils openvpn stunnel4
Use 'sudo apt autoremove' to remove them.
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.  

Сегодня я немного погуглил об этом и нашел эти три команды, однако не знаю, как их точно написать:

export QTDIR="/path/to/qt-5.0.1"
export PATH="${QTDIR}/bin:${PATH}"

Есть эта переменная, которая может быть полезна при работе с cmake:

export CMAKE_PREFIX_PATH="${QTDIR}"

Он добавляет путь к Qt к пути поиска Cmake.