diff --git a/CMakeLists.txt b/CMakeLists.txt
index 1d5717d9f..223d064f1 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -72,14 +72,14 @@ endif(CMAKE_BUILD_TYPE MATCHES Release)
 # Configuring compilers
 if ("${CMAKE_CXX_COMPILER_ID}" STREQUAL "Clang")
 	# using Clang
-	set(CMAKE_CXX_FLAGS "-Wall -Wno-unknown-pragmas -Wno-unneeded-internal-declaration -pedantic -fPIC")
+	set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wall -Wno-unknown-pragmas -Wno-unneeded-internal-declaration -pedantic -fPIC")
 	message(STATUS "OpenMP parallelization not available using clang++")
 elseif ("${CMAKE_CXX_COMPILER_ID}" STREQUAL "GNU")
 	# using GCC
-	set(CMAKE_CXX_FLAGS "-Wall -fopenmp -pedantic -fPIC")
+	set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wall -fopenmp -pedantic -fPIC")
 elseif ("${CMAKE_CXX_COMPILER_ID}" STREQUAL "Intel")
 	# using Intel C++
-	set(CMAKE_CXX_FLAGS "-static-intel -wd10237 -Wall -openmp -ipo -fPIC")
+	set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -static-intel -wd10237 -Wall -openmp -ipo -fPIC")
 elseif ("${CMAKE_CXX_COMPILER_ID}" STREQUAL "MSVC")
 	# using Visual Studio C++
 endif()