diff --git a/CMakeLists.txt b/CMakeLists.txt
index 8edbe00..b447b9a 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -9,7 +9,7 @@ if (NOT CMAKE_BUILD_TYPE)
 endif()
 if(CMAKE_CXX_COMPILER_ID STREQUAL "Intel")
   set(IntelComp true )
-elseif(CMAKE_CXX_COMPILER_ID MATCHES "GNU*")
+elseif(CMAKE_CXX_COMPILER_ID MATCHES "GNU*" OR CMAKE_CXX_COMPILER_ID MATCHES "Clang*")
   set(GNUComp true )
 elseif(CMAKE_CXX_COMPILER_ID MATCHES "pgc*")
   set(PGIComp true )
@@ -26,9 +26,9 @@ if( (BUILD_RELEASE) OR (BUILD_PRODUCTION) )
     set(CMAKE_Fortran_d_FLAGS "-r8 -O3 -fp-model strict -ip -FR " CACHE INTERNAL "" )
     set(CMAKE_Fortran_4_FLAGS "-O3 -fp-model strict -ip -FR " CACHE INTERNAL "" )
   elseif(GNUComp)
-    set(CMAKE_Fortran_d_FLAGS "-O3 -ffree-form -fdefault-real-8" CACHE INTERNAL "" )
-    set(CMAKE_Fortran_4_FLAGS "-O3 -ffree-form " CACHE INTERNAL "" )
-  elseif(PGIComp)
+    message("setting gnu flags")
+    set(CMAKE_Fortran_d_FLAGS " -fdefault-real-8 -O3 -ffree-form " CACHE INTERNAL "" )
+    set(CMAKE_Fortran_4_FLAGS " -O3 -ffree-form " CACHE INTERNAL "" )
   else()
     message("unknown compiler!")
     exit()