diff --git a/CMake/options.cmake b/CMake/options.cmake
index cc7060bd8..8e8ee02e4 100644
--- a/CMake/options.cmake
+++ b/CMake/options.cmake
@@ -300,7 +300,7 @@ if (UNIX)
         pkg_get_variable(LIBDECOR_LIBDIR libdecor-0 libdir)
         set (LIBDECOR_PLUGIN_DIR ${LIBDECOR_LIBDIR}/libdecor/plugins-1)
         if (EXISTS ${LIBDECOR_PLUGIN_DIR} AND IS_DIRECTORY ${LIBDECOR_PLUGIN_DIR})
-          set (LIBDECOR_PLUGIN_DIR "\\\"${LIBDECOR_PLUGIN_DIR}\\\" " )
+          set (LIBDECOR_PLUGIN_DIR "\"${LIBDECOR_PLUGIN_DIR}\"" )
         else ()
           set (OPTION_USE_SYSTEM_LIBDECOR OFF)
         endif ()
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index d6a7a047c..dcac1ae61 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -520,17 +520,29 @@ if (OPTION_USE_WAYLAND)
     set (CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -DHAS_DBUS")
   endif (DBUS_FOUND)
   if (OPTION_USE_SYSTEM_LIBDECOR)
-    set (CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -DUSE_SYSTEM_LIBDECOR")
-    set (CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -DLIBDECOR_PLUGIN_DIR=${LIBDECOR_PLUGIN_DIR} ")
+    set (CDEFS "USE_SYSTEM_LIBDECOR;LIBDECOR_PLUGIN_DIR=${LIBDECOR_PLUGIN_DIR}")
     if (GTK_FOUND)
-      set (CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -DHAVE_GTK")
+      set (CDEFS "${CDEFS};HAVE_GTK")
     endif (GTK_FOUND)
+    set_source_files_properties(
+      ${CMAKE_CURRENT_SOURCE_DIR}/../libdecor/build/fl_libdecor-plugins.c
+      PROPERTIES COMPILE_DEFINITIONS "${CDEFS}")
   else()
-    set (CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -I${CMAKE_CURRENT_SOURCE_DIR}/../libdecor/src  -I${CMAKE_CURRENT_SOURCE_DIR}/../libdecor/src/plugins  -DLIBDECOR_PLUGIN_API_VERSION=1 -DLIBDECOR_PLUGIN_DIR=\\\"\\\" ")
-    set (CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -DUSE_SYSTEM_LIBDECOR=0 -DHAVE_MEMFD_CREATE -DHAVE_MKOSTEMP -DHAVE_POSIX_FALLOCATE")
+    set (IDEFS "${CMAKE_CURRENT_SOURCE_DIR}/../libdecor/src"
+      "${CMAKE_CURRENT_SOURCE_DIR}/../libdecor/src/plugins")
+    set (CDEFS
+      "USE_SYSTEM_LIBDECOR=0;LIBDECOR_PLUGIN_API_VERSION=1"
+      "HAVE_MEMFD_CREATE;HAVE_MKOSTEMP;HAVE_POSIX_FALLOCATE"
+      "LIBDECOR_PLUGIN_DIR=\"\""
+    )
     if (GTK_FOUND AND OPTION_ALLOW_GTK_PLUGIN)
-      set (CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -DHAVE_GTK")
+      set (CDEFS "${CDEFS};HAVE_GTK")
     endif (GTK_FOUND AND OPTION_ALLOW_GTK_PLUGIN)
+    set_source_files_properties(
+      ${CMAKE_CURRENT_SOURCE_DIR}/../libdecor/build/fl_libdecor.c
+      ${CMAKE_CURRENT_SOURCE_DIR}/../libdecor/build/fl_libdecor-plugins.c
+      ${CMAKE_CURRENT_SOURCE_DIR}/../libdecor/src/os-compatibility.c
+      PROPERTIES COMPILE_DEFINITIONS "${CDEFS}" INCLUDE_DIRECTORIES "${IDEFS}")
   endif (OPTION_USE_SYSTEM_LIBDECOR)
 
   list (APPEND CFILES