diff --git a/CMakeLists.txt b/CMakeLists.txt
index 1811ef5..dbf7ac9 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -12,7 +12,7 @@ set(CMAKE_CXX_EXTENSIONS ON)
 
 option(BUILD_TESTS "Build tests" OFF)
 
-set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Bsymbolic-functions -Wall -Wextra -Wpedantic -Wno-unused-parameter -Wno-missing-field-initializers -Wno-switch")
+set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Bsymbolic-functions -Wall -Wextra -Wpedantic -Wno-unused-parameter -Wno-missing-field-initializers -Wno-switch -Wl,--no-undefined")
 
 find_package(ECM REQUIRED NO_MODULE)
 set(CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH} ${ECM_MODULE_PATH} ${ECM_KDE_MODULE_DIR})
diff --git a/src/libinputactions/config/parsers/triggers.cpp b/src/libinputactions/config/parsers/triggers.cpp
index 9fb2ab2..c0318ba 100644
--- a/src/libinputactions/config/parsers/triggers.cpp
+++ b/src/libinputactions/config/parsers/triggers.cpp
@@ -19,6 +19,7 @@
 #include "triggers.h"
 #include "NodeParser.h"
 #include "containers.h"
+#include "flags.h"
 #include "separated-string.h"
 #include "utils.h"
 #include <libinputactions/conditions/ConditionGroup.h>