diff --git a/external/external_build.cmake b/external/external_build.cmake
index fa2442b..3b266bb 100644
--- a/external/external_build.cmake
+++ b/external/external_build.cmake
@@ -5,13 +5,9 @@ OPTION(ENABLE_OPENMP "Set to Yes if Healpix and/or you need openMP" OFF)
 IF(ENABLE_OPENMP)
 
   IF (NOT OPENMP_FOUND)
-    MESSAGE(ERROR "No known compiler option for enabling OpenMP")
+    MESSAGE(FATAL_ERROR "No known compiler option for enabling OpenMP")
   ENDIF(NOT OPENMP_FOUND)
 
-  SET(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} ${OpenMP_C_FLAGS}")
-  SET(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${OpenMP_CXX_FLAGS}")
-  SET(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKED_FLAGS} ${OpenMP_C_FLAGS}")
-
 ENDIF(ENABLE_OPENMP)
 
 SET(BUILD_PREFIX ${CMAKE_BINARY_DIR}/ep_build)